Move some base classes into the API

Add Javadocs for API classes that didn't already have them

Redo

'nother redo

Another redo

Update ItemSigil.java

Last one, I swear

Fix

src/main/java/WayofTime/bloodmagic/client/IVariantProvider.java

@@ -6,6 +6,5 @@ import java.util.List;
 
 public interface IVariantProvider
 {
-
     List<Pair<Integer, String>> getVariants();
 }