With Boost 1.72.0, if the sinusoidal comparison and the sinusoidal
serialization tests are in the same test file, the tests succeed, but
are followed by a "free(): invalid pointer" exception, marking the test
as failed.

This makes no sense, but the workaround is trivial.

Add piecewise::load_from_text_file

New curves type required by sot-talos-balance

Use Bezier formulation for cubic hermite

Check input degree before converting curve to bezier or hermite

remove cubic and quintic classes