add tab cycle key to setting GUI
fixes #2791 don't crash on powerdown hotkey when playing cnc
pull cnc sell/repair button hotkeys from settings
fixes #2785 don't crash when last player leaves game in cnc
move order button hotkey logic to ingame chrome logic

removes power-down again from cnc mod as it is not wanted there
Merge pull request #2801 from Mailaender/hotkey-cleanup

Remove inconsistencies that crash C&C mod