[RFC] Refactor into standalone build scripts.

[fwalch]

A build is here, output (from multiple builds) in fwalch/doc2.

From the updated readme:

To generate individual reports locally, execute ./ci/<build script>, where build script is any executable shell script. Override environment variables as necessary, e.g. NEOVIM_REPO=<username>/neovim NEOVIM_BRANCH=my-branch ./ci/clang-report.sh.

I think this also improves high-level readability of report generation quite a bit:

# clang report
DOC_SUBTREE="/reports/clang/"
install_dependencies
clone_doc
clone_neovim
generate_clang_report
commit_doc

Next step is to install only required dependencies for each report (ref #12).

[fwalch]

This environment variable is set by Travis.

[fwalch]

Rebased from master. Now suppresses all output from git push instead of just using --quiet to make sure that the token won't leak even in case of an error (ref #15).

[fwalch]

Changed to a more detailed commit message and fixed infinite loops on Travis for neovim/bot-ci forks. This occurred because the decrypted GH_TOKEN is of course not accessible in forks, so if Travis was enabled and e.g. this PR's branch was built after pushing, it would repeatedly try to push without the token (resulting in Anonymous access to neovim/doc.git denied.) until Travis timed out the build.

You have to add a separate commit to test PRs on Travis; I added instructions for that to the readme.

From my point of view, this is ready.

[fwalch]

@justinmk What do you think of this? There are a lot of modified files in this PR, but not that many code changes. I tried to sum them up in the commit message.

[justinmk]

Very nice instructions. I learned something :)

[fwalch]

Thanks :-)