Moved the room destroy button on the left and visually separated it from the other buttons...

This is more coherent for the player.
Did the same for traps...
Adapted the main menu to lower resolutions

The menu is still ok on higher ones...
Adapted the skirmish menu to lower resolutions

Up to 640x480...
Adapted the join game menu to lower resolutions...
Adapted the host game menu to lower resolutions...
Adapted the editor loading menu to lower resolutions...
Merge pull request #223 from Bertram25/development

Some work on GUI