Fixed code with max proj cone option

Fixed line 1684 error and provided sandbox option to mess with max cone spread.

Update that fixes a couple things that makes gameplay better. I have tested the update and everything works fine. However, if a new bug that has not been mentioned is discovered, let me know.

- XP modifiers actually work now
- Zombie collision code has been tweaked so players can't damage zombies behind them when shooting in the opposite direction. It may still happen but it's very very unlikely. I still need to put some work into it.
- Arrows and bolts appear in zombie's inventory now (credits to Lisola)
- Tweaked with projectile logic. I narrowed the cone a bit so the bullet no longer goes 90 degree off to the side. Bullets spawn closer to the character to make point blanks a lot easier.
- Attachment system is overhauled. It tries to give a good balance between vanilla and Brita's attachments.

-shooting through open windows no longer smash them

-added compatibility with shotguns in "Scrap Guns"

Fixed issue with combat text not functioning (health bar was not appearing when zombies were hit by bullets)

- improved wall collision with bullets, shooting in tight spaces should not be as problematic as before
- added modifiers for player damage (PVP)
- buffed player damage
- fixed issue with chainsaw (brita's)
- fixed issue with flamethrowers shooting bullets (brita's)
- shooting point blank is more consistent

- fixed issue with player not getting xp when zombie is shot by player (players gains a bit of xp when not missing)
- buffed xp when killing zombie
- added modifier for xp gained when hitting or killing zombies

- fixed major bug where melee was not working when multi hit is enabled

- Added option to enable zombie outlines (still need to check outline option in pz's vanilla settings)
- Tidied up the sandbox options

Huge thanks to lisola (author of Improved Projectile) for helping me