Windows had an issue where it was trying to build the CFFI module after
it had already imported the CFFI module. Which caused permissions
errors during builds.
This fix does several things to make the Windows build work properly and
improve the Linux build too:
* The CFFI module is only build when needed, not as part of an sdist
package
* Version numbering spilt out into separate file so __init__.py import
is not required
* Merged _build_ffi.py and _build_wolfssl.py into one file
* Made CFFI only build when called as an executable (which happens
during binary build time)
* Make tox use bdist-wheel instead of sdist
1. sdist based build/test works now. Better to use that.
2. switch to py3 instead of py39 to better suit older versions.
3. remove pep8 testing for now, some more work needed for that.
* Fix some path and compiler things for Windows
* Move source code to align better with Python standards
* Have setup.py build wolfSSL and FFI
* Update Python versions in tox
* Add CMake building for Windows build
* Add missing __init__.py for tox
* Make wolfSSL a git submodule
Andrew Hutchings
Moisés Guimarães