* include/freetype/config/ftheader.h: removed obsolete macros like
	FT_SOURCE_FILE, etc.. and added cache-specific macro definitions that
	were previously defined in <freetype/ftcache.h>. Added comments to be
	included in a new API Reference section.

	* src/*/*: removed the use of FT_SOURCE_FILE, etc.. now, each component
	needs to added its own directory to the include path at compile time.
	Modified all "rules.mk" and "descrip.mms" accordingly..