This PR extends the custom sphinx extension for examples. It now allows for simple patterns in the file names and matches the file types using arbitrary regular expressions instead of just looking at the file extensions. This is necessary to integrate examples from the z3pycompat API: the examples live at a nontrivial place (in the build folder), which we inject via the file name patterns; we will have two separate examples which both end in .py but can be distinguished via the pattern used in the beginning.
This PR includes documentation for the z3py compatibility API into our general API.
It does so by adding the z3py compatibility API as an external project to download it and then have sphinx document it via the autodoc extension that we already use for our regular python API.
Right now we simply show everything on one page, which should be refactored in the future.
This PR adds documentation to the python class Op, Grammar, Result, and for API enums.
Additionally, documentation for isNull functions in the datatype classes is added for the python API, and a small change in the cpp API documentation is introduced.
