[uilib] allow canvas tags in the html cleaner Used by the iprogress cube. Closes #3524254.

[ajax] use a custom tag to handle dynamically loaded js Using <pre class="script"> makes it trivial for a malicious user to inject arbitrary javascript into a html or rest text element (because it looks innocent to the html sanitizer). Using a custom tag we can be sure that it actually comes from our code and not from untrusted user data. IE ignores custom tags, though, so we put it in its own namespace. https://extranet.logilab.fr/1530578

[dataimport] fix comment

[hooks/security, devtools/fill] silence yams 0.38.0 warnings

Drop 3.13 incomplete backward compat in edit controller. It is very old and broken (there is another non-backward-copmpatible usage of `_cw_entity_fields`), better to remove it instead of fixing. Closes #3515223.

[devtools] force locale to C for postgresql test clusters Avoids initdb failure with e.g. iso8859-X locale and utf-8 encoding.

[rql2sql] remove special behaviour of symmetric relation vs DISTINCT 0542a85fe667 replacing SQL OR by hooks for symmetric relations allows that. This involve a single test value change for a border case: when querying a symmetric relation without specifying the subject nor the object, you may get some duplicated result. IMO this is fine to let the user explicitly use DISTINCT or not and to remove the dedicated handling we had which didn't let any choice. Related to #3259713

Typo in comments and error messages

Fix typo in a setup.py comment

[dataimport, migration] more fixes in the spirit of a6c32edabc8d: [entity, metadata] huuum, use resolvable url as cwuri... And fix existing ones. Closes #3390388