Add initial tests for piecewise surface minimum_distance

Specified initial guess only.  01 parameters only.
Make minimum_distance surface work with piecewise surfaces with non 01 parameter
Check vmin/vmax edges independently of u_closed status for min_dist_surface.
Make min dist curve more permissive like surface variant.

This may trigger when Newton's method exits with a different exit code.
If the solution is valid and improved, we should still use it.
Simplify min dist surface with no initial point given.