Teach scripts about git version

[zbeekman]

Avg response time	coverage on master

Summary of changes

More clever version information in install.sh --version, extracted by CMake and in caf --version and cafrun --version

Rationale for changes

The "odd patch level version number between releases" was getting a bit annoying, and I wanted an easier way to tell which commit a users code is based on. Now it should be possible, under most circumstances to easily get this information.

One exception is when someone does a shallow clone... since git describe won't be able to track back to a tag, but this is fine, since it should still have the commit hash... so where we need something that looks like x.y.z (e.g., CMake project version) we fall back on the embedded version in .VERSION

If the user is using an official release tarball then .gitattributes to embed additional information in .VERSION file including:

• ref-names (this is the magic sauce to get the tag info)
• Git commit that the generated archive was based on
  • Full hash
  • Committer name
  • Committer date
  • Commit signer and pubkey
  • Signature status and output of gpg verify

So just make sure to git checkout <tag> before git archive --prefix=OpenCoarrays-$(git describe)/ -o OpenCoarrays-$(git describe).tar.gz <tag> to have the cleanest info in .VERSION. (It will still work if you don't checkout the tag first, you'll just add info about where your current HEAD is at...)

Additional info and certifications

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• Bug fix
• Feature addition
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[codecov]

Codecov Report

Merging #393 into master will decrease coverage by 4.11%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #393      +/-   ##
==========================================
- Coverage   41.19%   37.07%   -4.12%     
==========================================
  Files           3        3              
  Lines        1277     1950     +673     
  Branches      227      320      +93     
==========================================
+ Hits          526      723     +197     
- Misses        665     1119     +454     
- Partials       86      108      +22

[zbeekman]

I'm going to merge this early because I have tested extensively locally, and would like to get this into the pending release, after going over the CI tests with a fine-toothed comb.

LGTM