OME-XML package bug-fix (rebased onto develop)



This is the same as gh-1022 but rebased onto develop.

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The class `OMEXMLMetadataImpl` used to live in `ome.xml.ome`, and the POM reflected that. But it has now moved to `ome.xml.meta` for consistency with other auto-generated classes; this change is necessary to reflect that.

Thanks to @rleigh-dundee for the solution!