This patch introduces a new report formatter for the mozlint
framework used by "./mach lint" that respects Unix output conventions,
popularised by grep(1), compilers, and preprocessors.
The output format looks like this:
testing/marionette/driver.js:1153:48: no-unused-vars error: 'resp' is defined but never used.
Many editors (ed, Emacs, vi, Acme) recognise this format, allowing
users to interact with the output like a hyperlink to jump to the
specified location in a file.
MozReview-Commit-ID: 3IyiFmNbtMY
440d933e70