Add planar_approx and optimized version of eqp_distance_bound.
Add planar_approx and optimized version of eqp_distance_bound.

The simplified version of planar_approx creates a bi-linear patch from
the four corner points of the current surface patch.  The patch order is
unchanged.

simple_eqp_distance_bound assumes that the patches being compared have
identical order and it performs no safety checks to that effect.

ramcdona/Code-Eli