* freedesktop.org.xml.in: Make "application/postscript",
	a subclass of "text/plain". Thanks to Sebastian Heutling,
	Tristan Wibberley and Sebastien Bacher.

	Add missing sub-classing information to a few dozen other
	MIME types, including "application/rtf", "application/pdf",
	ODF and OOo MIME types.

	* Makefile.am:
	* test-subclassing.c:
	Add simple XML parser that checks for presence of "sub-class-of"
	nodes in freedesktop.org.xml and outputs MIME types that don't
	provide the flag.