This PR introduces a new sub-crate, `ignore`, which primarily provides a
fast recursive directory iterator that respects ignore files like
gitignore and other configurable filtering rules based on globs or even
file types.
This results in a substantial source of complexity moved out of ripgrep's
core and into a reusable component that others can now (hopefully)
benefit from.
While much of the ignore code carried over from ripgrep's core, a
substantial portion of it was rewritten with the following goals in
mind:
1. Reuse matchers built from gitignore files across directory iteration.
2. Design the matcher data structure to be amenable for parallelizing
directory iteration. (Indeed, writing the parallel iterator is the
next step.)
Fixes#9, #44, #45
This commit completes the initial move of glob matching to an external
crate, including fixing up cross platform support, polishing the
external crate for others to use and fixing a number of bugs in the
process.
Fixes#87, #127, #131
