Ripgrep code review

I'd like to respond to a few of the bad things pointed out. :P

The search code is indeed in a less than ideal state. I've mostly avoided refactoring it because I want to move it to its own separate crate. I've been steadily doing this for other things. Namely, ripgrep used to be a single main crate plus a small regex handling crate (grep), but now it's several: globset, grep, ignore, termcolor and wincolor. I'd like to roll the search code into the grep crate so that others can use it. Once that's done, ripgrep proper will be a pretty small, limited mostly to argv handling and output handling.

I do sometimes get overzealous with inline(always) and inline(never). Both are almost always a result of trying things while profiling, and then forgetting to remove them. If you look closely, most of them are in the core searching code where performance is quite important!

Finally, this code review was done while I was in the middle of moving more of ripgrep code out into the `ignore` and `termcolor` crates. The `ignore` crate does all the gitignore handling (which is quite tricky and is now being used by the tokei project: https://github.com/Aaronepower/tokei) and provides a parallel recursive directory iterator, which made ripgrep even faster! The `termcolor` crate handles cross platform coloring shenanigans, including Windows consoles and mintty. It wasn't fun: https://github.com/BurntSushi/ripgrep/issues/94#issuecomment... --- The author did a great job reviewing the previous solution I used for colors though, and was something I really wasn't proud of!