generated/javatests licenses

[glelouet]

Small fix to add the licence so the generated class files.
Copied from the JCMWriter to dicover the classes from the packages

• lists the classes of the packages
• hidden classes are discarded
• classes with already a header are discarded (even if empty header)
• subclasses are not walked over.
• add the header LICENCE to the selected classes.

@phax I let you change what needs change.
maybe run sh/cleaninstal before merging ?

[glelouet]

I was thinking of extracting the classes iteration in a dedicated JCM proxy field
something like Stream<JDefinedClass> JCM#classes::rootClasses , with classes the proxy field (basically a structure to contain existing classes listing etc)