Improves RT window position management, fixes #6233 (#6239)

* Improves RT window events detection and RT window position computation

* Fixes some limitations in specific cases for Windows and MacOS

* Fixes RT window not restoring saved position at startup

- When maximized at startup, RT window position wasn't restored from
options file. So when unmaximazing RT, position was set to up left
corner instead of restored one
- Other fix: Removed some uses of deprecated Gtk functions

* Improves RT window management for independant edit window mode

Other fixes:
- Monitor ID wasn't correctly computed
- Removes some other deprecated functions uses
- Removes debug printf

* Fixes editor window aspects not restored in MEOW mode on Linux

Other fixes:
- Removes some Gtk warnings when adding a new editor panel in MEOW mode
- Adds robustness to avoid RT windows outside screen at startup loading
corrupted options file with negative position values

* Fixes incorrect max position saturation in dual screen configurations

rtgui/options.h

@@ -219,7 +219,6 @@ public:
     bool windowMaximized;
     int windowMonitor;
     int meowMonitor;
-    bool meowFullScreen;
     bool meowMaximized;
     int meowWidth;
     int meowHeight;