[test] fix ReST extensions tests

[web/controller] fix some cases where _cwmsgid may appears twice the Way the URL was build led to double _cwmsgid parameter in the URL query, which led in turn to a crash. We use _cw.rebuild_url to update new params instead of append_url_params which merely does a textual concatenation.

[reledit, autoform] move reledit_form definition in reledit.py No deprecation handling needed, reledit_form is new in CW 3.15