Remove some leftover turret configuration.
Remove defense computer config files.
Half drill and leech construction time.
Fix turret by adding back attackType to config file.
Use G_FireWeapon for all weapon modes, take weapon as an argument.
Remove buildableAttribute_t.turret*.

Buildable attacks are generally too varied and complex for generic config files.
Remove buildableAttribute_t.nextthink.

Setting think perdiods can have side effects and should only be done inside the think function.
Fix alien buildables firing without an overmind.