* 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 all tools supplying documentation, as we use some specific
software to create the doc, they may not be available, or worse, be
and incompatible version. So, by default, we install the files shipped
with the git repository. To force a full doc rebuild, use the "--doc"
flag of ccb.py.