* New: Isobar::PyAttributesHolder, a PyObject with only a dictionary
to hold the attributes associated to a DBo.
* New: Isobar::PyHolderProperty, the Property that encapsulate
PyAttributesholder.
* New: Isobar::PythonAttributes, the extension to simplify the
management of the PyAttributesholder.
* Change: In PyEntity, now use a dedicated tp_getattro and tp_setattro
to delegate the Python attribute access towars the PyAttributesholder.
* New: In hurricane/doc & documentation, update docs regarding Python
attributes managment.
* Change: In documentation, now generate the overall documentation using
Pelican instead of Sphinx. This allows to have an unified approach
between the coriolis.lip6.fr website and the local documentation.
So we keep using "only" two doc generators: doxygen & Pelican.