Add initial support for QtIndenticon

Add initial loading of qt jdenticon plugin:
https://github.com/redsky17/qt-jdenticon

Currently, the library's functionality has not been integrated
into the rest of nheko.  Next step is to add a configuration
item in the User Settings and use the plugin to generate
avatars for users without their own picture.  These avatars
should be cached in the Cache object.

src/MainWindow.cpp

@@ -19,6 +19,7 @@
 #include <QLayout>
 #include <QSettings>
 #include <QShortcut>
+#include <QPluginLoader>
 
 #include <mtx/requests.hpp>
 
@@ -166,6 +167,10 @@ MainWindow::MainWindow(QWidget *parent)
 
                 showChatPage();
         }
+
+        if (loadJdenticonPlugin()) {
+                nhlog::ui()->info("loaded jdenticon.");
+        }
 }
 
 void
@@ -479,3 +484,27 @@ MainWindow::showDialog(QWidget *dialog)
         dialog->raise();
         dialog->show();
 }
+
+bool
+MainWindow::loadJdenticonPlugin()
+{
+    QDir pluginsDir(qApp->applicationDirPath());
+
+    bool plugins = pluginsDir.cd("plugins");
+    if (plugins) {
+        foreach (QString fileName, pluginsDir.entryList(QDir::Files)) {
+                QPluginLoader pluginLoader(pluginsDir.absoluteFilePath(fileName));
+                QObject *plugin = pluginLoader.instance();
+                if (plugin) {
+                        jdenticonInteface_ = qobject_cast<JdenticonInterface *>(plugin);
+                        if (jdenticonInteface_) {
+                                nhlog::ui()->info("Found jdenticon plugin.");
+                                return true;
+                        }
+                }
+        }
+    }
+
+    nhlog::ui()->info("jdenticon plugin not found.");
+    return false;
+}