Initialize some LyX colors from Qt. Currently what is done is plain text and selectio...

Initialize some LyX colors from Qt. Currently what is done is plain text and selection (both font and background).

I am not sure that there is something else that we can get from QPalette. Maybe
cursor color, if someone tells me how to get it.

Only tested on mac. I can revert if this causes problems on linux or windows.

I have to check too that it still works in non-gui mode.

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@35060 a592a061-630c-0410-9148-cb99ea01b6c8