Implement weapon inaccuracy

[ClobberXD]

Implement inaccuracy, and implement increased accuracy when aiming down sights. This feature would replace the lame 20% additional damage when aiming down sights.

• Spread (f4cdc15)
• Recoil (7999179)
• Bullet drop

[ClobberXD]

f4cdc15 implements spread. What's left to do is to somehow reduce spread if player is aiming down sights.

[ClobberXD]

Bullet drop should also be implementable if using progresssive raycasting (#27) or entity-based projectile handling (#25).

[skittlemittle]

do you want to reduce spread when scoped or remove spread when scoped?

[ClobberXD]

Yeah, reducing spread when the player is scoping is what I'd like to see. But ideally, the amount of reduction in spread (i.e. increase in accuracy) should be customisable per-weapon (or per-addon when addon support is added later).

[ClobberXD]

Forgot to note, recoil has been added in 7999179

Only bullet drop remains. I'll implement this after #27.