Fix formulas for Linear.Plucker's plucker/><
Fix formulas for Linear.Plucker's plucker/><

These functions seem to be incorrect. The replacement formulas are taken from:
http://tog.acm.org/resources/RTNews/html/rtnv10n3.html#art11

phaazon/linear,meteogrid/linear,bgamari/linear,isomorphism/linear