HFrame(char* namein, PSpace& ins, GeObList& t)
Builds a projective frame for the projective space ins, using the objects in the list t, after they are mapped into ins if necessary. The projective frame creates its own copy of the debug name given in the buffer namein.
HFrame(Basis& f)
Used to downcast a general basis to a projective frame. Only succeeds if the general basis is holding a projective frame.