[ADD] port security reference doc
[ADD] openerp.http reference doc

* fix some docstrings so they can be autodoc'd
* intersphinx mapping (and links to) werkzeug and python
[ADD] web client tutorial/training

needs fixes, and corresponding web client reference
[FIX] http.py: session id is `sid` attribute
fix typo on undeclared variable xml_id
Merge pull request #2113 from yvaucher/8.0-fix-ir_model-undefined-xml_id

fix typo on undeclared variable xml_id
[FIX] crm: lead_to_opportunities, check that current active_id has not been already merged by another previous active_id. Else, we was trying to browse an lead which was already deleted by a previous merge in the same loop.
[IMP] models: do not prefetch too many records at once
[IMP] models: prefetch fields with groups (those to which user has access)