Mods can now define new BlockFamily implementations.
Removed code that was moved to other classes.
Fix the issues with BlockFamilyFactories loading.
Getting rid of "instanceof" for BlockFamily testing.
Merge branch 'blockFamily' of https://github.com/MarcinSc/Terasology into blockFamily
Polishing the code.
Merge pull request #525 from MarcinSc/blockFamily

Block family refactoring