Map/gametype vote layout changes
Improvements over the map/gametype vote screens:
- items as big as possible with minimum alteration of the desired item aspect ratio (like in the weapons panel layout)
- layout more compact with limited item size (especially with very few vote choices)
- added a background in the default hud skin, as part of the change that makes them real panels
- fixed a few minor things
- the fps panel (if enabled) is kept on screen during the map vote