* 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.

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

The goal is to reduce the memory consumption.

  isPluged -> isPlugged.

  - add isPlugged and getPlugged methods,
  - add property getter name.

pointed out by OS.

This is crucial when debugging remotely using winpdb.

Make possible to read the output from the process lauching the process.

This corrects the issue detailed here:
https://github.com/jrl-umi3218/dynamic-graph-python/issues/2

Solution found by Florent Lamiraux.

Pointed out by A. Mallet.