Rename convention

navipy/maths/constants.py

navipy/maths/euler.py

navipy/maths/homogeneous_transformations.py

navipy/maths/quaternion.py

navipy/maths/test_euler.py

navipy/maths/test_homogeneous_transformations.py

navipy/maths/test_quaternion.py

navipy/processing/test_OpticFlow.py

navipy/trajectories/test_markers.py

navipy/trajectories/test_trajectory.py

navipy/trajectories/transformations.py