Some warnings, some globals hunting.
Including fixes for asserts misuse (possible fatal for async in release
builds).

workaround for #1533

Rationale:

- It is not a part of eSpeak-NG, nor useful wrapper/adapter
- It is not properly documented and maintained
- It is unsafe (running PHP daemon with user privileges and [launch
ANY](6d7101c03c/chromium_extension/index.php (L8))
received command via
[passthru](https://www.php.net/manual/en/function.passthru.php) -
seriously?)

Workaround for NVDA's broken SSML.


7c08cf52fe/source/synthDrivers/espeak.py (L336-L339)

fix single characters transcription for б, ж, й, ў

fix single characters transcription for б, ж, й, ў

- fix IPA chars for "s;" and "z;" phonemes
- add bug note about "...i a..." case

- fix IPA chars for "s;" and "z;" phonemes
- add bug note about "...i a..." case

Fixes: #1547

- Implement building and testing with cmake
- Download libsonic from repository (when enabled and not available as
system library), ref: #650
- Migrate android native build to cmake
- Migrate CI to cmake
- Add windows CI

TODO (might be done in separate PR):
- Building as [cmake external
project](https://cmake.org/cmake/help/latest/module/ExternalProject.html)
- Building for package managers (deb, rpm, ...)
- Strip out `vcproj` - _to be discussed_
- Strip out `autotools` after next release
- Update build documentation for `cmake`