macosx: Improve VLCHUDCheckboxCell
macosx: Improve VLCHUDCheckboxCell

Improve drawing and colors of the Checkbox Cell for
use on dark HUD panels.
This still requires a bit work but looks ok now.

xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc