Type annotations issues with documentation

[McSinyx]

There are two separate issues with the type hinting in the documentation at the moment (either generated by Python's help or Sphinx):

• Embedded signature uses Cython syntax even if source code does not (Generate Python typing compatible text signatures (and stubs) cython/cython#3150), e.g. query_extension(str name: str) -> bool
• Properties' type signatures are not shown in doc (bpo-39125)

Until these get fixed upstream, there should be work-arounds (especially for number 2, whose fix is unlikely to be backported to, say, Python 3.6 which we want to support).

If time allows, we can try to patch the first one upstream. Cython codebase is huge to study but it is not impossible.

Edit: To elaborate, the first one is caused by the signature generated by Cython when embedsignatures compiler directive is set to True, which add prepend each docstring with the function's signature (which is otherwise missing due to, welp, that's common for extension types). To work around this, we can simply turn off this directive and add the signature manually, which I find ugly but not too ugly. Another choice is to set binding=True, but currently it wraps types in single quotes, e.g. query_extension(name: 'str') -> 'bool'. I have yet to find the issue documenting that bug, maybe it's time to file the issue on Cython. As described in PEP 563, query_extension(name: 'str') -> 'bool' is totally an excepted behavior.

[McSinyx]

(1) can be solved by switching Cython binding on, once sphinx-doc/sphinx#7331 and bpo-39990 are fixed.

Edit: With the Sphinx issue being fixed, palace 0.1 will be shipped with bindings (yay!).