Improve build

[MischaPanch]

Closes #31 #22

The caching is extra-careful: there is only one cache key which is pinned to the branch and to requirements.txt, setup.py and tox.ini. Any change in those files invalidate the previous cache

[MischaPanch]

Speedup due to caching is noticeable (below with the previous dependencies as benchmark). Since with this PR we get one more env and more dependencies, the speedup will be even higher

Note that the very first build on a branch/PR will actually be a bit slower (cache needs to be uploaded) but all subsequent builds will be faster

[opcode81]

I can't test this because the tox build does not work under Windows.
I trust that you've verified the correctness, thus approved.
Just to clarify one thing: The relaxed depdendencies come in via the "full" specification in extras, i.e. this indirectly makes use of what we specified if setup.py - correct?

[MischaPanch]

I can't test this because the tox build does not work under Windows.
I trust that you've verified the correctness, thus approved.
Just to clarify one thing: The relaxed depdendencies come in via the "full" specification in extras, i.e. this indirectly makes use of what we specified if setup.py - correct?

Precisely. This is done by omitting -rrequirements.txt in the dependencies of the tox env. Then it pulls the dependencies from setup.py

[MischaPanch]

Btw, you can see the correctness in the build logs. I have verified that in the new env the newest versions of the packages are installed