[Development Feature] Add travis CI pipeline about betterfountain

[piersdeseilligny]

@rickschubert sounds good! I don't really have any experience with this but you're right, it definitely wouldn't be a bad thing. I've added you as a collaborator.

[rickschubert]

I will close this ticket for now as well as my pull request. I wanted to open it as an issue to see how your opinion is but it actually isn't really an issue, more a feature suggestion. I will close my pull request #73 for now. The pipeline itself was set up and working, but the tests aren't passing anymore - and nobody wants to merge in a pipeline with failing tests.

I had a glimpse at fixing the tests but since the screenplay statistics now also require the afterparser to run as well as the PDF creation, the tests can't run in isolation anymore and would have to be run on a VSCode host. I might look into it in my spare time out of personal interest but want to close it for now so as to not have a stale pull request on the repository and thereby maybe give the impression to other contributors that contributions wouldn't be welcome.