Finishing touches for hexen compatibility (1.1 update):

- Fully implemented ammo cubes.
 - Fixed environment map shaders (incorrect texture coords were being used).
 - HUD support for displaying Hexen keys.
 - Fixed "has no ammo" messages displaying more often than they should.
 - Fixed lack of footsteps with UT physics disabled.
 - Sneaky initial Strife compatibility work:
   - Impact Hammer will have reduced alert distance.
   - HUD support for displaying Strife keys.

textures.misc

@@ -21,3 +21,4 @@ Sprite "CHIPA0",1,1{}
 Sprite "USKLA0",1,1{}
 Sprite "UKEYA0",1,1{}
 Sprite "RNGXA0",1,1{}
+Sprite "ABOXA0",1,1{}