ELM compilation should generate an episode file

[sotty]

The ELM XSD is imported by other schemas, e.g. the KNART XSD Applying XJC to the parent schema results in the re-generation of the ELM classes, which instead should be loaded from the ELM jar. To prevent this, it is sufficient to generate an "episode" file that can be used during the compilation of the schemas that import ELM

Proposal: ... ${xjc.args} -npa -XautoInheritance .... To: "${xjc.args} -npa -episode elm.episode -XautoInheritance ...

(same for other schemas)

[brynrhodes]

Seems like a reasonable change to me, are there any potential impacts to existing schema usage?