If there are uncommitted changes use `git-clang-format` to limit the style
fixups to the lines being modified.
Refuse to do a `make style-all` if there are uncommitted changes.
Include a fix for the parsing of `git status` output that was recently
incorporated into the lint.fish script.
Include information about how to deal with lint warnings and suppress
`clang-format` reformatting of blocks of code.
Move information only relevant to developers from the README.md to the
CONTRIBUTING.md document.
Closes#2901
This changes implements two new make targets: `style` and `style-all`. These
make it easy to ensure that a change conforms to the project style guides for
C++ and fish code.
Fixes#571
