Add CI configuration and tests, perform simple fixes

[honzajavorek]

Implements and closes #13. Doesn't make the tests pass, because I was unable to debug the following problems:

/Users/honza/Projects/emojicodes/docs/source/index.rst:5: WARNING: Inline emphasis start-string without end-string.
/Users/honza/Projects/emojicodes/docs/source/index.rst:5: WARNING: Inline emphasis start-string without end-string.
/Users/honza/Projects/emojicodes/docs/source/index.rst:5: WARNING: Inline emphasis start-string without end-string.

If those are fixed, I believe the tests will pass. Under honzajavorek#1 it should be visible how it works.

The Windows tests will probably fail as well even when the other will pass, because I'd say make won't be installed out of the box, but that can be later fixed simply by choco install make I think. Let's see. It'd focus on making it pass on Linux/macOS now. Also, perhaps it doesn't make sense to test the docs on multiple OS'es and it's okay to test it just on Linux. We'd test on multiple OS'es only if we have real tests for the code. But so far I'm keeping what I have as a demonstration of what's possible if we make it pass, and we can expand on that / restructure it later.

[Peque]

@honzajavorek Thanks for having a look at this! 😊

I have nothing against GitHub Actions (or any other CI service integration). I would, however, prefer to make it easy for developers to be able to run the tests locally. Also, that eases any possible CI service migration in the future.

I would use Tox for this. See for example osbrain's Tox configuration and how Travis runs just Tox.

Could you try to put the CI checks in a tox.ini file and then run the tests with Tox from GitHub Actions? 😇

[honzajavorek]

Oh, tox supports running arbitrary commands? I thought it's just for tests of code (e.g. pytest), that's why I skipped it for this stage (also, the wording used in #13 made me think introducing tox could be a next step).

[Peque]

@honzajavorek Yeah, you are right interpreting #13. However, since it seems you are on a streak I thought maybe we could take advantage and hit two targets with one shot! 😜

[honzajavorek]

I'll check out tox, but no promises about timing :)