cleanup and micro-optimization

[web action] has_editable_relations should not filter out final relations, fix regression introduced in 6358:22c95c5ef12d

[c-c] fix RuntimeError: 'maximum recursion depth exceeded while calling a Python object' we get when creating/upgrading/shelling an instance: hasattr() call __getattribute__, creating an infinite recursion error catched by the interpretor. Avoid this by testing the method is available on the class instead of the instance

[transaction] to avoid potential db corruption, we should rollback systematically in case of ValidationError

[selector] cleanup

[sync schema] take care rdef may not be final, in which case we want to use type of eid attribute

[web action] has_permission_update checked implicitly by has_editable_relation, don't check it twice

[muledit] form may contains subforms with nothing editable that will be s kipped, so ensure we choose one with something to display when rendering table headers

[c-c i18n] namespace/line wrap cleanup + dynamically compute available language + make it works in installed mode

[i18n] no more necessary, those msgids are no more generated

[wf component] reversing selectors here may be a huge performance win on big rsets, since EntityVComponent selector starts with one_line_rset

don't add another encoding if already present in content-type

[book] note about different encryption on Unix and Windows

make reset-admin-pwd work with sqlserver as db backend the pyodbc sqlserver db backend depends on being passed the cw_upassword value as a buffer object to bind it to a binary column (which is usually done when CW is dealing with passwords).

[book] updated FAQ 'How to reset the password for user joe' with SQL Server syntax