Problem: When canceling the preferences dialog after changing a color then the icon...

Problem: When canceling the preferences dialog after changing a color then the icon in the colors list is not reverted after reopening the dialog. Moreover when pressing apply later then the color is really changed.

Solution: Move the color initialization from the constructor to the update() method. I've read the mail from Richard (referenced in the source code) concerning this, but i don't understand why we should not move parts of the initialization the constructor does into the update method. With this changes the hack for fixing http://bugzilla.lyx.org/show_bug.cgi?id=3109 is not needed.

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@18249 a592a061-630c-0410-9148-cb99ea01b6c8