Adds bronze & copper stuff to Mineclone 2.

Bronze item - 80% durability of iron, but dig_speed_class + 1.
Bronze sword - speed = speed diamond sword, 80% durability of iron.
Bronze armor - protection = chainmail armor +1 , 80% durability of iron. 
Copper stuff - 80% durability of bronze.

! tin is not realized, use an iron ingot to obtain bronze.

ALTERNATIVE RECIPES:
(instead of an iron ingot, a bronze one, but the functions of the items are the same).
- Bucket
- Rails
- Shield


RECIPES:
- Broze Armor
- Bronze tools: shovel, sword, pickaxe, axe, shears, hoe...
- Bronze Ingot
- Copper tools: shovel, hoe, shears...

