UI|Client: Improvements for popup menus and Home Screen

Adjusted style of popup menu labels. Added some labels to the
App menu.

Moved the game sort order choice to the left side so it doesn't go
under the notification area.
Fixed|libdoom|libhexen: Compiler warnings (missing initializers, unused args)
Fixed|Renderer|Client: Benign compiler warning (value used before initialization)
Merge branch 'master' of github.com:skyjake/Doomsday-Engine
Merge branch 'master' into id1-import