merge develop -D org -I include -E exclude: PR 512 (xsd-fu: Extend C++ support to generate headers and include guards)
merge develop -D org -I include -E exclude: PR 518 (ScanR: clear the pixel buffer when an invalid TIFF is found (rebased onto develop))
merge develop -D org -I include -E exclude: PR 519 (.cxd dimension detection fixes (rebased onto develop))
merge develop -D org -I include -E exclude: PR 521 (Assorted bug fixes for May)