Topic/doc spline

See merge request loco-3d/curves!5

Edit doc of cubic_spline, exact_cubic, quintic_spline, spline_deriv_constraint. Modify name of variables min and max to t_min and t_max.

CMake: clean

See merge request loco-3d/curves!3

Fix evaluation of bezier of degree 0 added, Edit doc on bezier_curve, Edit assert_allclose to assertTrue in test.py

Devel

See merge request loco-3d/curves!2

Refactoring

See merge request loco-3d/curves!1

Edit file name spline_python.cpp to curve_python.cpp, in test.py edit TestSpline and test_spline to TestCurve and test_curve, edit all makefiles, make test 100% OK

change namespace spline to curve in include folder, rename folder spline to curve, change in the CmakeList.txt

sync with hpp-spline master

fix python tests

And also check that AssertionErrors are not silenced