[doc] typo

[cw-ctl] fix help message for schemadiff In global help (closes #2888538) The leading space make it appears on multiple line. The help content is a bit improved in the process.

[dbapi] fix connect backwards compat harder Passing None as group and host should result in "pyro:///cubicweb.appid", not "pyro://None/None.appid". Followup for 2091d275fe5c. Closes #2882666.

[zmq] make publish address optional It should be possible to use the zmq communication bus in a read-only manner. Allow setting zmq-address-sub without zmq-address-pub. Closes #2897178.

Fix documentation for zmq pub/sub hooks and configuration Closes #2897177

[entity] improve deprecation messages

[devtools] use self._parse so AssertionError is properly raised instead of lxml error (test failure introduced in 6711f78c18be)

[testlib] fix page validator selection. Closes #2869456 * use a validator that checks XML well-formness for the html5 doctype (as a convenient side-effect, it does not choke on e.g. a canvas tag like the HTMLParser does) * use a DTD validator if there is an xml declaration * else use the HTMLValidator

[testlib] introduce a validator that check xml-well formness This validator simply check XML is well formed and accept any entities (think HTML defines much more entities than bare XML)

[view] return HTML5 doctype. Closes #2869426 We dropped xhtml support in 3.17 but we kept providing documents using the XHTML strict doctype, while our content wasn't conform to the DTD since we dropped proper namespaces definition as well as declaration of cubicweb DTD extensions.