Replaces Perp Bisector finding code to give lines which actually work.
I guess previous cde was broken, but not entirely sure why.

Signed-off-by: John Lawson <john@jwlawson.co.uk>
Changes hyplinefactory perpbisector to include minuses that were missed

Signed-off-by: John Lawson <john@jwlawson.co.uk>
Trying to decrypt voronoi code

Signed-off-by: John Lawson <john@jwlawson.co.uk>