Extras: Don't mess with the barrel's mass, please

It screws with a lot of BOOM-compatible maps which rely on barrel
explosion chains to trigger events at certain times, causing them to
execute way too early.
Extras: A bunch of missing sounds re-added

Also reworked some of the SndInfo.
Extras: Fix more Arachnotron problems
Extras: Buff chainsaw to act like the original

I also merged the hold and fire states together.
One person doesn't justify "a group"
Merge branch 'master' of https://github.com/Kyle873/DoomRPG
Helps if I put it in the right spot
Extras: Pistol needs Ammo2
Extras: Some more effects tweaking, fix monsters
Merge remote-tracking branch 'remotes/origin/master' into menurewrite