Fix warnings an typos

include/ndcurves/bezier_curve.h

include/ndcurves/constant_curve.h

include/ndcurves/cubic_hermite_spline.h

include/ndcurves/curve_abc.h

include/ndcurves/helpers/effector_spline_rotation.h

include/ndcurves/linear_variable.h

include/ndcurves/optimization/details.h

include/ndcurves/piecewise_curve.h

include/ndcurves/se3_curve.h

include/ndcurves/sinusoidal.h

include/ndcurves/so3_linear.h

python/ndcurves/curves_python.cpp

python/ndcurves/python_variables.h

python/test/optimization.py

python/test/sandbox/test.ipynb

python/test/sandbox/varBezier.py

python/test/test.py

tests/Main.cpp