Syndicate shotguns to replace the eguns

Shotguns:
- Initially loaded with taser slugs
- Extra ammo is pretty economical from the uplink
- Replace boring eguns, makes nuke ops more ballistic-focused
- Leave trails of spent shotgun shells whereever you go

Other changes:
- Tweaked some descriptions
- Tweaked some file path names for shotgun ammos
- Tweaked some names

Pics later
Sprites by ausops
src.loc works better anyway, now everyone will know when ops are out of ammo and mob them with batons.