add per-room user model

src/UsersModel.cpp

@@ -0,0 +1,28 @@
+#include "UsersModel.h"
+
+#include "Cache.h"
+#include "CompletionModelRoles.h"
+
+#include <QPixmap>
+
+UsersModel::UsersModel(const std::string &roomId, QObject *parent)
+  : QAbstractListModel(parent)
+{
+        roomMembers_ = cache::getMembers(roomId, 0, 9999);
+}
+
+QVariant
+UsersModel::data(const QModelIndex &index, int role) const
+{
+        if (hasIndex(index.row(), index.column(), index.parent())) {
+                switch (role) {
+                case CompletionModel::CompletionRole:
+                case CompletionModel::SearchRole:
+                case Qt::DisplayRole:
+                        return roomMembers_[index.row()].display_name;
+                case Avatar:
+                        return roomMembers_[index.row()].avatar;
+                }
+        }
+        return {};
+}