More stuff before public release.

Adjust the aspect of new 0.83 hud icons.
Impaler plays unique sound when ending altfire instead of select sound.
Adapt some things for the old sounds add-on.
Minor HUD adjustments (weapon slot related).
Left a couple notes of what I might do next.

Readme.md

@@ -78,6 +78,9 @@ Doom Tournament (currently the devel branch is required).
 
 ## Planned
 
+ - Impaler "slice" animation for melee alt
+ - Separate proto content into an add-on (if people want)
+
  - RTNP add-on
  - Monster pack (someday)
  - Map pack (maybe? who knows)