Fix #25: Introduce multiple levels of failures

[abesto]

Highlights:

• Can now differentiate between "check failed" and "failed to run check" (latter gets printed as [ERROR])
• Individual checks can return various error levels, depending on the severity of problems they find. For example, the build-and-test check reports a FAIL level problem if it knows how to run tests, but they fail; on the other hand it reports a NOTE level problem if it doesn't know how to run tests.
• Inline problem reporting is correctly colorized by level (with NOTE level stuff not colorized to prevent rainbow-induced confusion, I'm running out of colors here)
• Repo-Release archive comparison is downgraded to WARN until #20 is done
• Advanced mathematics are utilized to correctly add padding to the [WARN] prefixes in the summary

[codefromthecrypt]

probably it would help my brain a lot to classify what are actually ASF requirements from what are not. There's no requirement to have the files in the source dist match the repo. The first couple repos we've done matched so mentally we are anchored to this concept. Since we are testing things that are not requirements and not necessarily even valid. It would be cool to order the ones that are concrete at the top, then a line or something, then the extra checks we made up which may help, but are not actually requirements at the bottom.

[abesto]

I like the idea of separating ASF-required and non-ASF-required checks, filing a task. I have concerns around "There's no requirement to have the files in the source dist match the repo", let's have that discussion on #20.