damagetype System

I added some code to weapon postdefs that allow for damage types; this basically allows damage multipliers against armor types to be defined for groups of weapons instead of per-weapon. Use the customParam “damagetype” to say that a weapon deals X type of damage, and in gamedata/damagedefs.lua, specify what multiplier that type of damage should get against armortypes. Damages explicitly defined in the weapondefs override the calculated values. This should be the best of both worlds between mass edits and unstructured postdef modifiers: no need to run edit scripts, and no confusing information in the weapondefs either. (Maybe this is what Tobi meant by “good design” back in a different topic =p)

The damagetype system has been implemented, with the exception of some explosions. Feel free to change any of the damage values, or the multipliers in gamedata/damagedefs.lua. At current default damage corresponds to armouredvehicles, since that is what I would say is the closest to a “typical” feature.

Currently all explosions are the same damagetype. Do we want larger explosions to be better against tanks than smaller ones beyond simply doing more damage to everything (e.g. by using the AP system)?