Mgc* files

Magic Software computational geometry routines,
downloaded from
	http://www.magic-software.com/http://www.magic-software.com/http://www.magic-software.com/http://www.magic-software.com/http://www.magic-software.com/http://www.magic-software.com/httphttp://www.magic-software.com/

The routines have been slightly tweaked (OSL 2003/8)
for speed-- several Mgc::Vector3 routines were moved
into the .inl inline file, and an early-exit test
was added to MgcIntr3dTetrTetr.