PrBoom WAD names

PrBoom works with multiple released versions of Doom, but has particular naming conventions you must follow if you want the Launcher to see the WAD file.

Doom	doom.wad
Ultimate Doom	doomu.wad
Doom II	doom2.wad
TNT: Evilution	tnt.wad
The Plutonia Experiment	plutonia.wad
Freedoom	freedoom.wad

This is particularily important because the Steam version of Ultimate Doom has the WAD file named doom.wad.