Bullet inscriptions

- Can inscribe text into bullets by using a screwdriver on a bullet casing (I think it was @Ravensdale that suggested this on IRC)
- Does not work on non-metal type bullets (i.e. rubber bullets, beanbags, stunshots, etc)
- Added weakbullet subtypes "rubber bullet" and "beanbag" with appropriate names

I can shorten the allowed text length if 20 characters seems too much.

I also did some work on allowing you to unload magazines and refill them, but the further I dug into the code the messier it got. Instead I just opted to PR the inscription changes for now.