[Bug] Tympan API hanging when opening a project with verbose=False

When calling project.from_xml from the python API, verbose needs to be set to True otherwise the API hangs when loading a project.

This appears to be due to the combination of the sys.stderr redirection performed by filter_output (tympan/model/__init__.py) and warning messages raised when opening the project.

Disabling the sys.stderr redirection or ignoring warnings can fix the problem, but it is still unclear why those two seem to not mix. Besides, disabling the warnings also prevents them from beeing shown when running Tympan.