Change to decay: different materials for repairs

[Granger]

Excellent idea Zamte, only one thing:

Other items like rams, ovens, smelters, crucibles, and every other item that is used for item processing, should take damage due to use (like plows currently do), but ONLY from use.

I think they should get damage from current decay system, but way less. Else they wouldn't be cleaned up over time.