`vel_start` and `vel_end` in `computePathParametrization()` handled differently

[mskripnik]

PathParametrizationAlgorithm::computePathParametrization(value_type vel_start, value_type vel_end)

vel_start is the path velocity squared at s=0
vel_end is the actual path velocity at s=1

This is not only not documented, but also very misleading.

[mishrasubhransu]

Yes. I had to change m_data.parametrization(0) = vel_start; to m_data.parametrization(0) = vel_start * vel_start; to make both of them path velocity.