Port RoomManager to C++

This also makes it possible to handle the Matrix URI

org.kde.neochat.desktop

@@ -70,7 +70,8 @@ Comment[sv]=Klient för protokollet Matrix
 Comment[uk]=Клієнт протоколу Matrix
 Comment[x-test]=xxClient for the Matrix protocolxx
 Comment[zh_CN]=为 Matrix 协议打造的客户端
-Exec=neochat
+MimeType=x-scheme-handler/matrix;
+Exec=neochat %u
 Terminal=false
 Icon=org.kde.neochat
 Type=Application