Re-arrange Metallurgy Ore Generation

* Orichalcum will still generate in TF Highlands because I want it to, I just set the material to generate in to deadrock, which hopefully makes it generate.
* Adamantium now generates in Thornlands, in place of Atlarus.  Again, I've set the material to deadrock to hopefully make it generate.
* Atlarus now generates in dark forests.  I've toned down the amount that it will generate as well, as 90 ores per chunk seemed a bit high.

This will hopefully fix #122, but will need some testing to confirm.