tidy-up: OS names

Use these words and casing more consistently across text, comments and
one curl tool output:
AIX, ALPN, ANSI, BSD, Cygwin, Darwin, FreeBSD, GitHub, HP-UX, Linux,
macOS, MS-DOS, MSYS, MinGW, NTLM, POSIX, Solaris, UNIX, Unix, Unicode,
WINE, WebDAV, Win32, winbind, WinIDN, Windows, Windows CE, Winsock.

Mostly OS names and a few more.

Also a couple of other minor text fixups.

Closes #14360

docs/libcurl/curl_getenv.md

@@ -27,7 +27,7 @@ char *curl_getenv(const char *name);
 
 curl_getenv() is a portable wrapper for the getenv() function, meant to
 emulate its behavior and provide an identical interface for all operating
-systems libcurl builds on (including win32).
+systems libcurl builds on (including Windows).
 
 You must curl_free(3) the returned string when you are done with it.
 
@@ -55,6 +55,6 @@ specified name.
 
 # NOTE
 
-Under unix operating systems, there is no point in returning an allocated
+Under Unix operating systems, there is no point in returning an allocated
 memory, although other systems does not work properly if this is not done. The
-unix implementation thus suffers slightly from the drawbacks of other systems.
+Unix implementation thus suffers slightly from the drawbacks of other systems.

docs/libcurl/curl_global_init.md

@@ -89,7 +89,7 @@ unexpected behaviors.
 Initialize the Win32 socket libraries.
 
 The implication here is that if this bit is not set, the initialization of
-winsock has to be done by the application or you risk getting undefined
+Winsock has to be done by the application or you risk getting undefined
 behaviors. This option exists for when the initialization is handled outside
 of libcurl so there is no need for libcurl to do it again.
 

docs/libcurl/libcurl-env-dbg.md

@@ -98,7 +98,7 @@ the current.
 
 ## CURL_TIME
 
-Fake unix timestamp to use for AltSvc, HSTS and CURLINFO variables that are
+Fake Unix timestamp to use for AltSvc, HSTS and CURLINFO variables that are
 time related.
 
 This variable can also be used to fake the data returned by some CURLINFO

docs/libcurl/libcurl-tutorial.md

@@ -112,7 +112,7 @@ specified are:
 ## CURL_GLOBAL_WIN32
 
 which only does anything on Windows machines. When used on a Windows machine,
-it makes libcurl initialize the win32 socket stuff. Without having that
+it makes libcurl initialize the Win32 socket stuff. Without having that
 initialized properly, your program cannot use sockets properly. You should
 only do this once for each application, so if your program already does this
 or of another library in use does it, you should not tell libcurl to do this
@@ -235,7 +235,7 @@ to make your program run fine virtually everywhere.
 (CURLOPT_WRITEDATA(3) was formerly known as *CURLOPT_FILE*. Both names still
 work and do the same thing).
 
-If you are using libcurl as a win32 DLL, you MUST use the
+If you are using libcurl as a Windows DLL, you MUST use the
 CURLOPT_WRITEFUNCTION(3) if you set CURLOPT_WRITEDATA(3) - or experience
 crashes.
 

docs/libcurl/libcurl.md

@@ -95,7 +95,7 @@ See libcurl-ws(3)
 
 # LINKING WITH LIBCURL
 
-On unix-like machines, there is a tool named curl-config that gets installed
+On Unix-like machines, there is a tool named curl-config that gets installed
 with the rest of the curl stuff when 'make install' is performed.
 
 curl-config is added to make it easier for applications to link with libcurl

docs/libcurl/opts/CURLOPT_CONNECTTIMEOUT.md

@@ -53,7 +53,7 @@ to 2, the operation can never last longer than 2 seconds. Including the
 connection phase.
 
 This option may cause libcurl to use the SIGALRM signal to timeout system
-calls on builds not using asynch DNS. In unix-like systems, this might cause
+calls on builds not using asynch DNS. In Unix-like systems, this might cause
 signals to be used unless CURLOPT_NOSIGNAL(3) is set.
 
 # DEFAULT

docs/libcurl/opts/CURLOPT_CONNECTTIMEOUT_MS.md

@@ -54,7 +54,7 @@ With CURLOPT_CONNECTTIMEOUT_MS(3) set to 4000 and CURLOPT_TIMEOUT_MS(3) set to
 the connection phase.
 
 This option may cause libcurl to use the SIGALRM signal to timeout system
-calls on builds not using asynch DNS. In unix-like systems, this might cause
+calls on builds not using asynch DNS. In Unix-like systems, this might cause
 signals to be used unless CURLOPT_NOSIGNAL(3) is set.
 
 # DEFAULT

docs/libcurl/opts/CURLOPT_HEADERDATA.md

@@ -36,7 +36,7 @@ If CURLOPT_WRITEFUNCTION(3) or CURLOPT_HEADERFUNCTION(3) is used,
 If neither of those options are set, *pointer* must be a valid FILE * and
 it is used by a plain fwrite() to write headers to.
 
-If you are using libcurl as a win32 DLL, you **MUST** use a
+If you are using libcurl as a Windows DLL, you **MUST** use a
 CURLOPT_WRITEFUNCTION(3) or CURLOPT_HEADERFUNCTION(3) if you set
 this option or you might experience crashes.
 

docs/libcurl/opts/CURLOPT_NOSIGNAL.md

@@ -27,7 +27,7 @@ CURLcode curl_easy_setopt(CURL *handle, CURLOPT_NOSIGNAL, long onoff);
 
 If *onoff* is 1, libcurl uses no functions that install signal handlers or
 any functions that cause signals to be sent to the process. This option is
-here to allow multi-threaded unix applications to still set/use all timeout
+here to allow multi-threaded Unix applications to still set/use all timeout
 options etc, without risking getting signals.
 
 If this option is set and libcurl has been built with the standard name

docs/libcurl/opts/CURLOPT_PROXY_SSLCERTTYPE.md

@@ -39,7 +39,7 @@ the format of your client certificate used when connecting to an HTTPS proxy.
 
 Supported formats are "PEM" and "DER", except with Secure Transport or
 Schannel. OpenSSL (versions 0.9.3 and later), Secure Transport (on iOS 5 or
-later, or OS X 10.7 or later) and Schannel support "P12" for PKCS#12-encoded
+later, or macOS 10.7 or later) and Schannel support "P12" for PKCS#12-encoded
 files.
 
 The application does not have to keep the string around after setting this

docs/libcurl/opts/CURLOPT_PROXY_SSLKEY.md

@@ -39,7 +39,7 @@ the filename of your private key used for connecting to the HTTPS proxy. The
 default format is "PEM" and can be changed with
 CURLOPT_PROXY_SSLKEYTYPE(3).
 
-(Windows, iOS and Mac OS X) This option is ignored by Secure Transport and
+(Windows, iOS and macOS) This option is ignored by Secure Transport and
 Schannel SSL backends because they expect the private key to be already
 present in the key chain or PKCS#12 file containing the certificate.
 

docs/libcurl/opts/CURLOPT_SSLCERTTYPE.md

@@ -38,7 +38,7 @@ the format of your certificate.
 
 Supported formats are "PEM" and "DER", except with Secure Transport or
 Schannel. OpenSSL (versions 0.9.3 and later), Secure Transport (on iOS 5 or
-later, or OS X 10.7 or later) and Schannel support "P12" for PKCS#12-encoded
+later, or macOS 10.7 or later) and Schannel support "P12" for PKCS#12-encoded
 files.
 
 The application does not have to keep the string around after setting this

docs/libcurl/opts/CURLOPT_SSLKEY.md

@@ -36,7 +36,7 @@ Pass a pointer to a null-terminated string as parameter. The string should be
 the filename of your private key. The default format is "PEM" and can be
 changed with CURLOPT_SSLKEYTYPE(3).
 
-(Windows, iOS and Mac OS X) This option is ignored by Secure Transport and
+(Windows, iOS and macOS) This option is ignored by Secure Transport and
 Schannel SSL backends because they expect the private key to be already present
 in the key-chain or PKCS#12 file containing the certificate.
 

docs/libcurl/opts/CURLOPT_TIMEOUT.md

@@ -55,7 +55,7 @@ With CURLOPT_CONNECTTIMEOUT(3) set to 4 and CURLOPT_TIMEOUT(3) set
 to 2, the operation can never last longer than 2 seconds.
 
 This option may cause libcurl to use the SIGALRM signal to timeout system
-calls on builds not using asynch DNS. In unix-like systems, this might cause
+calls on builds not using asynch DNS. In Unix-like systems, this might cause
 signals to be used unless CURLOPT_NOSIGNAL(3) is set.
 
 # DEFAULT

docs/libcurl/opts/CURLOPT_TRANSFERTEXT.md

@@ -26,7 +26,7 @@ CURLcode curl_easy_setopt(CURL *handle, CURLOPT_TRANSFERTEXT, long text);
 # DESCRIPTION
 
 A parameter set to 1 tells the library to use ASCII mode for FTP transfers,
-instead of the default binary transfer. For win32 systems it does not set the
+instead of the default binary transfer. For Win32 systems it does not set the
 stdout to binary mode. This option can be usable when transferring text data
 between systems with different views on certain characters, such as newlines
 or similar.

docs/libcurl/opts/CURLOPT_URL.md

@@ -81,7 +81,7 @@ expected to be a sequence of characters using an ASCII compatible encoding.
 
 If libcurl is built with IDN support, the server name part of the URL can use
 an "international name" by using the current encoding (according to locale) or
-UTF-8 (when winidn is used; or a Windows Unicode build using libidn2).
+UTF-8 (when WinIDN is used; or a Windows Unicode build using libidn2).
 
 If libcurl is built without IDN support, the server name is used exactly as
 specified when passed to the name resolver functions.