Fixes and re-arrangement of the (advanced) codegeneration stuff.
The CPP/D/Java/Ruby classes are now more of interfaces to their own settings (in optionstate.h) + their manipulation than storage classes of the settings itself.

/me believes it fixes the bugs in the advanced code generation. Oliver, can you confirm ?

All the configuration options for the code generators are now read in uml.cpp file than their own files.

(except the common configuration options. That's because they are common to all. Maybe I should move them to uml.cpp too, but that'd be later, perhaps)