Add conversion cubic hermite to cubic bezier,test ok

include/curves/CMakeLists.txt

include/curves/bezier_polynomial_conversion.h

include/curves/cubic_hermite_spline.h

include/curves/curve_conversion.h

include/curves/exact_cubic.h

include/curves/piecewise_curve.h

python/curves_python.cpp

python/test/test.py

tests/Main.cpp