View source for Kexi/Main Window/Full screen

*DONE
*{{Wish|298880}}
*Target milestone: 2.5

Full screen is going to be used with small screen computers, namely netbooks etc.
There going to be two different modes implemented but called from different places in the UI.
*Kexi MainWindow fullscreen:
**Decorations will be hidden
**Tabbar will be hidden
**Will get called using F11
*Tab (part fullscreen):
**Single KexiWindow fullscreen:
**Hiden everything except Current KexiPart.
**If in design mode, have design tabs auto hide to the top.