Fix CustomBlock for obfuscation

These mappings will be human readable once 1.7.4 Forge is recommended. We
can handle a couple of fields easily for now :P.

Also remove another un-needed class: LanguageRegistry. Multilingual
support may come down the road but it is supposrted differently in Forge
10.x +. This also goes for the CommonConnectionHandler

Lastly, manually merged @Snaipe 's ReflectionUtil class from his PR for
master branch. I needed it :P.

Signed-off-by: Chris Sanders <zidane@outlook.com>