[REF] html_email_clean: refactoring of the algorithm, now better taking into account hotmail / msoffice emails. Added tests.
[IMP] html_email_clean: now handles maximum character number truncature.
[REF] html_email_clean: refactored the algorithm to clean it, specifically about truncature. Now add classes to node when not removing them, to be managed by the web client.
[MERGE] Sync with trunk
[MERGE] Sync with trunk
[ADD] test_workflow: added some tests for the workflows.
[DOC] workflows: started to write some workflow documentation.
[DOC] workflows: added Conditions section.
[IMP] workflows: added docstring, some variable renaming (to wkf_expr).
[DOC] workflows: added Signals section.
[DOC] workflows: improved Triggers section.
[DOC] workflows: added Flow start and flow stop section.
[DOC] workflows: added Subflow section.
[DOC] workflows: added remaining sections for the Activities.
[DOC] workflows: added Kinds section.
[ADD] workflows: added some tests.
[ADD] workflows: more tests.
[ADD] workflows: some split_mode tests.

I am not sure if the Workflow K is determinist though
so it could maybe end up in activity c instead of b
(and thus fail the tests).
[FIX] workflows: fixed the non-deterministic workflow K, added workflow L in tests.
[ADD] module views: add css for html description (wip)