Merge pull request #575 from rleigh-dundee/omexml-screenref

ome-xml: Remove ScreenRef
merge develop -D org -I include -E exclude: PR 528 (Tile performance improvements for VMS and NDPI)
merge develop -D org -I include -E exclude: PR 572 (2013-06 schema links)
merge develop -D org -I include -E exclude: PR 573 (bfopen: save individual series' original metadata)
merge develop -D org -I include -E exclude: PR 574 (xsd-fu: Generalise language type mapping)
merge develop -D org -I include -E exclude: PR 577 (Update auto-generated documentation)