Add CI github actions workflow

[sethaxen]

As discussed on slack, this PR sets up a github actions CI that builds all of IMP and runs the test suite with code coverage, uploading to codecov.

[sethaxen]

@benmwebb do you have any idea why ctest doesn't find the tests?

[sethaxen]

@benmwebb thanks for the changes. Is this now superseded by the ci.yml workflow in the default branch?

[benmwebb]

Is this now superseded by the ci.yml workflow in the default branch?

No, that in develop is just a stopgap - it does what the old Travis build used to do (just compilation, no tests). (Travis builds stopped working for all our repos because we ran out of credits, so I switched them all to GitHub Actions.) I'd like to run a basic set of tests too, as you're doing here. Something in the nose environment doesn't look quite right yet though (probably because it's trying to run everything in one process, and the tests weren't written with that in mind). I'm gradually replacing nose with pytest in our repos, so I'll probably do that here too rather than mess with nose for too long (unless you want to look at it instead).

[sethaxen]

Something in the nose environment doesn't look quite right yet though (probably because it's trying to run everything in one process, and the tests weren't written with that in mind). I'm gradually replacing nose with pytest in our repos, so I'll probably do that here too rather than mess with nose for too long (unless you want to look at it instead).

I'll take a stab at it, but no promises.

[codecov-io]

Codecov Report

:exclamation: No coverage uploaded for pull request base (develop@e5c226f). Click here to learn what that means. The diff coverage is n/a.

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