Option to spawn souls from gun kills

* Added the requisite code to each DECORATE monster
* Controlled by the ds_gunsouls CVAR, defaulted to off
Sword Tweaks

* Reduce startup & cooldown on charged launcher
* Remove negative recoil from launcher to prevent overshoot when air chasing
butts.txt
Apparently this is going all over the internet, so.
oops
Merge pull request #12 from ShiftyAxel/gunsouls

Option to spawn souls from gun kills
Merge pull request #15 from ShiftyAxel/sword-tweaks

Sword Tweaks
stuff
ds_gunsouls now changed from ACS-based to inventory-based for less packeting.
Add ds_dropammo CVar to control zombie ammo drops

* Added MaybeClipDrop, MaybeBigClipDrop and MaybeShellDrop actors
* Checks ds_dropammo and spawns the correct amount of ammo if true
* Improves balance when using level mods that eschew ammo for zombies