Double initial guess for the surface kink position.

Double initial guess for the surface kink position.

The previous algorithm would fail for curves if
1) They didn't have many tension features to stretch out the range.
2) The contact slope "softened" a bit in the kink region.

For example, try it on most of the test/vclamp_picoforce data ;).

The new algorithm works perfectly on the ideal, boring curve:
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