WIP: Big GUI overhaul

- New in game window
- Lots of refined controls, such as edit box, list box, mouse cursor, ...
- Dropped suplicated controls in looknfeel
- Dropped a lot of old skin. The old skin left in use is only done for non-used control types yet.
- Added the game version in the main menu.
- Started making windows out of loading screens.
- Added the necessary controls to later add map description when clicking on the list.

All this is WIP but was already a lot of work. :D