The great persistence fix

Add: The PropertyPersistenceTest checks whether the JAXB persistence system built into Classmod works.
Fix: The ObjectAdapter is located in the .extra.def package where it is actually needed.
Add: jaxb.index files which list the classes JAXB needs for performing serialization using a context path. Also add the .util.Classmod class which contains the default context path for Classmod.
Fix: The ObjectAdapter performs a workaround for collections too.
Fix: The whole persistence system works in general.