- Add new skin-colors: EGDC_GRAY_WINDOW_SYMBOL, EGDC_EDITABLE, EGDC_GRAY_EDITABLE, EGDC_FOCUSED_EDITABLE
- Make sure disabled state is extended to sub-elements.
- Fix that icons in tabcontrol get also affected immediately by skin-changes
- Make disabled state for several elements more visible


git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@3433 dfc29bdd-3216-0410-991c-e03cc46cb475