Haiku coding guidelines and haiku-format

[owenca]

@owenca

I think it would be interesting to start using the tool as part of our automated checks when patches get uploaded to Gerrit. It would save a lot of comments about formatting, and automate checking a decent part of our style guide.

I have updated the installation script in dc7ccf5 to generate git-haiku-format. Instead of running haiku-format -i changed_file.cpp to reformat the entire file, now you can run git haiku-format changed_file.cpp to only reformat the diff.

See here for a demo.

Thank you all for the feedback! As I said here, I’ll update haiku-format to 17.0.5 in about a month when the clang-format of the same version is expected to be released.