Regression may have been introduced about MONOSITE mode

- updated scripts etc
- make tests pass

Theorically all of those imports were tested by unit testing, but we've got no inssurance about that.
And even if unit tests had check for syntax errors, all pieces of code were not tested. We cannot
be sure that an import was missed or forgotten...

Before when session restore fails the webui was answering "Unknown status 200" as content.
Now it produce 2 log messages (maybe)

SLIM is now able to edit configuration from CLI, to start instances etc.

- webui fix in cookies handling
- ram_session fix in token generation (return an str : hex representation of os.urandom(n))
- more fixes in Client session handling

- Implemeting Client in plugins/webui/client.py
- Calling client in run.py

- webui now calls a hook to indicate a session end
- loader.py now set a lodel.dyncode module exposing dynmically generated code

- load variables from settings
- import loader.py

- create_instance.sh create some symbolic links
- webui plugin that add webui configuration variable