Pause Menu: Version Info

[JJL772]

This is a pretty simple HUD element that just displays some info about the game and how it's running.

Something like this in the bottom right corner would work:

P2CE - Alpha <Version str>
<Graphics API>
<Physics Engine> Physics

Relies on #44

[vrad-exe]

Could have this show the map name too when the console is open, I do find it annoying that that no longer appears in the top right.