This reverts commit 0d0fa66c.

* as a container of the signals created with create_signal_wrapper.
* This makes them available to other entities via the pool.

This allows accessing the list of entities instanciated in the dynamic-graph.

update badges

[CI] add .gitlab-ci.yml

Correct the run_python_file command + boost 1.50 compatible + win32 compatible

Former version crashed in case of syntax error
(cf test_syntax_error.py)

This crashes for most recent versions of boost

Correct branch and email information.

Improve the interpreter

This unit test shows that after a given number of run
of the same file, the error changes.
Unfortunately, this can not be automatically verified, since
the result is printed in the python error stream, and cannot be
redirected.

Add a method to test the existence of a signal.