Add a way to disable the compositor or at least VSync

[antunnitraj]

The Idea

Adding a way to toggle the compositor just like in KDE using a keybind (eg. Alt + Shift + F12) or with CLI like in XFCE:
xfconf-query -c xfwm4 -p /general/use_compositing -s false
xfconf-query -c xfwm4 -p /general/use_compositing -s true

Why?

Most games use "unlocked FPS" and the X11 compositor starts to act out therefore making the game look like its running on low FPS. Some games that use fullscreen are unable to trigger the "on fullscreen disable compositor" trigger so that has been a deal breaker for me. I really like Cinnamon but that bugged me a lot so i ask you all to do this change.