Iguana's Tinker Tweaks, Tweaks

Hooray for redundant mod names!  Anyways, I nerfed a few things here too:

- Normal Hoes are disabled, that's what the mattock will be used for.
- Nerfed Silky Jewel recipe, because silk touch 2 OP.
- Removed the diamond & emerald modifier because steel is available.
- No bonus modifiers; you get whatever's given to you, end of story.
- Removed mob head boosts, they're kind of silly anyways.