[python] Rationalize Python dependencies

[duburcqa]

Remove dependency to h5py, trimesh, scipy, and tree:

• tree: parse of variable names structure for variable registration. It could even be moved to C++, or boost::python bindings.
• h5py: read hdf5 log files. It could be implemented in boost::python bindings.
• trimesh: convert convex in bounding boxes. hppfcl is already capable of doing so.
• scipy: spline interpolation of 1D sequences.

[duburcqa]

h5py, scipy, and tree are no longer jiminy_py dependencies. trimeshis still planned to be remove sooner or later.

[duburcqa]

Dependency to dm-tree actually got removed more recently, than advertised (#706)