This patch adds ability to override qTox window and tray icons with ones from user's desktop theme. Some people prefer keeping tray icons consistent to achieve best looks.
Following theme icons used:
* qtox: general window icon which is also used in taskbar
* qtox-online, qtox-offline, qtox-busy, qtox-away, qtox-invisible, qtox-event: tray icons
If theme icon is not available then default built-in icon will be used.
Make the page directly accessible from the main screen by clicking the avatar or the username. Changing the avatar or the username are now possible only from the profile page
Added null checks around usage of tray icon object.
This change solves issues/crashes where tray is not immediately available when qTox is started. It is common on linux desktops. While for example lxqt has option to delay application autostart until panel (and thus tray) is available other desktops (like KDE) do not. Adding checks around use of icon object was not enough because application may start a little bit earlier than panel is available. For that reason tray icon creation is delayed to timer event and tried multiple times with delay of one second. Usually after few tries icon creation succeeds and signal is disconnected.
In case tray is not available qTox window is shown. This creates a side effect where starting qTox before tray is available will make application window briefly appear and when tray is available window will be hidden or remain visible as per settings. Window has to be visible if tray is unavailable because otherwise users may end up with qTox running and no way to access it. If application is started and tray is available no window flashing happens and settings are restored as usual.
Without this patch if qTox started before tray is available window is shown and changing tray icon visibility option crashes application. Thats probably a known issue.
We create a GUI class to abstract common GUI needs (showing a message box, asking a question, ...) from the actual GUI backend.
We also create a Nexus class to manage the startup and lifetime of our main systems (Core, GUI, ...) instead of delegating that to Widget.
Eventually, Widget will only be in charge of the Desktop GUI and AndroidGUI of the mobile GUI. Nexus will overview the system and GUI will provide a clean platform-independant interface.
