Reworked the command registration system

Please read the [javadoc](https://github.com/Limeth/Terasology/blob/16965803d4edd128ce5baaa3c35e814de26752f3/engine/src/main/java/org/terasology/logic/console/Command.java).
Class name case issue here - file is Neo class is NEO :-)

Beware that renaming filename capitalization only ... can be tricky. Might be easier to change the class name in the file