Added Chromium, Steel, and Stainless Steel

Only the ingots though, chromium ore (and generation) will come later.

Recipes:

Steel:
0C0
CIC
0C0
(0=nothing, I=Iron,C=Coal)

Stainless Steel:
SSS
SCS
SSS
(S=Steel,C=Chromium)
(Produces 9 Ingots)