This deserves some explanation.
* tests were moved to separate python/tests subdir
* trezorlib was moved to python/src, so that it does not exist on
PYTHONPATH by default
(see https://blog.ionelmc.ro/2014/05/25/python-packaging/ for details)
* everything was updated to understand the new structure
* trezorctl was changed from a top-level executable script to a module
`trezorlib.cli.trezorctl` and is installed via the entry_points
mechanism.
This should make it work normally on Windows!
The package should be installable as normal through pip and pipenv, no
changes are needed on that side.
The source package from pypi will include unit tests. (Device tests were
completely moved out). Wheel will exclude them, because users don't need
them.
That shrinks the .whl from 520 kB to 270 - nice!
python: reorganize remaining unit tests
