REVERSEPLANE Return same 3D plane but with opposite orientation.

   IP = reversePlane(PLANE);
   Returns a plane contining the same ppints but with normal opposite to
   that of PLANE. 
   If PLANE has the format [x0 y0 z0 dx1 dy1 dz1 dx2 dy2 dz2], then IP
   will have following parameters: [x0 y0 z0 dx1 dy1 dz1 -dx2 -dy2 -dz2].

   See also:
   createPlane, reverseLine3d

Package: matgeom