Fix: Wrong values for elements for enums in JSON output

With the recent introduction of the JSON generator, a 'values' variable
was added to EnumDef. "Definitions" only sorted 'keys', so keys were
given the wrong values. The C++/Nuria generator was not affected as
it only uses the keys and lets the compiler find the values when the
output file is compiled.
Removed unused methods in nuriagenerator.cpp

Forgot to remove these methods when I split Generator into
NuriaGenerator and Definitions.