[Modeling-users] ModelMasons refactored

[Sebastien B. <sbi...@us...>]

Ok, the refactor of ModelMasons/ModelMason.py and PyModelMason.py is
checked in.

  The default behaviour has slightly changed:

  - before: the building process stops if the target directory already
    exists

  - now: the generating process do not stop any more. Rather, it ignores
    the files that already exists. The only files that are overwritten
    are model_<modelName>.xml and model_<modelName>.py.

Please update the following files:
    scripts/mdl_generate_python_scripts.py v1.3
    ModelMasons/ModelMason.py v1.6
    ModelMasons/PyModelMason.py v1.7

  Next step on this will be to integrate the 'Base' generation-scheme,
  as discussed earlier on the mailing-list (with a patch proposed by
  soif).

I quickly checked that my models are correctly generated from python &
ZModeler, I'll appreciate if someone could double-check.

-- S=E9bastien.