ui: reworded voice chat settings, ref #226

Reworded to keep some logic with the cg_noVoice{Chat,Text} cvar.
The cvar themselves aren't changed to keep some commonality with
existing implementation in other mods.
ui: updated extended hostgame bottom bar

Add a three buttons bar at the botton, to make it easier to goes back
to the 'advanced' menu or directly to the main hostgame page.
Merge pull request #40 from Spyhawk/uifixes

ui: various minor ui fixes.