Update: weapons, new graphics, bugfixes (and probably new bugs)

What's new:

• New pickup type: weapons! A pistol (a straight shooter) and a grenade launcher (fires a bouncy grenade). Both weapon projectiles can kill players and enemies; grenades also damage other stuff.
• New box / pickup graphics.
• Cannons now have muzzle flash particle effects.
• A bunch of internal changes that might have introduced bugs (possibly regressions) to target or box related stuff; hopefully not a lot.
• Bugfix: if a crossbow was placed very close to the safezone, arrows could kill players inside.