Large crate bonuses, ent loader

-Large volume crates (2x4x4+) have bonus ammo and confer a bonus to fire
rate or reload time.
-2x4x4 is +10% ammo, +2% fire rate / reload speed bonus
-4x8x8 is +50% ammo, +10% fire rate / reload speed bonus
-Guns without clips get a fire rate bonus, guns with clips have a reload
speed bonus instead
-Updated gun definitions so they are defined similarly to engines --
each gun class has its own file