backport stable

[rqlrewrite] test and fix rql snippets insertion when several snippets match an optional variable

[datafeed, cw.xml] xml now carry entity's source information, interpreted at the other end so that for instance when an entity from elo is seen when importing cwo, it's properly marked as coming from elo source if one exists

[datafeed] actually raise on error

[python 2.5] compat fix

[datafeed, cwxml] parser now try to complete source's urls so one can add url such as <myinstance>/project. Closes #1759908

[server] fix unicode conversion capability in UndoException By overriding the __unicode__ method, we ensure unicode builtin will return Unicode object even for python versions that don't have a __unicode__ method by default (python < 2.6) In previous versions, when this method is not defined, string conversion is attempted, and the result of string conversion is converted to Unicode using the system default encoding which is ascii the most of the time.

[book] add autoload section from code and fix sphinx warnings * drop misleading faq entry since clear explanation can be found in internationalization chapter * use autodata sphinx directive instead of raw text * fill empty chapter with autodoc: - devweb/httpcaching.rst - devweb/resource.rst - devweb/views/idownloadable.rst - devweb/views/wdoc.rst * use shebang in excerpt to denote shell code * fix some bad indented docstrings in javascript files

[controller] fix wrong view name when error occurs in UndoController

[datafeed] renaming parser attribute to parser_id makes things clearer

cleanup and assert we don't import unexpected stuff

[source config] fix synchronization on configuration entity changes

[ui, sources] configure source form: hide synchronizing and mapping entities, use simple text input for parser

[rql annotation] fix bad invariant variable w/ has_text relation: this is only true when has_text will be used as principal (though we don't know that yet)