This brings the code in line with my current style. It also inlines the
dozen or so lines of code for FNV hashing instead of bringing in a
micro-crate for it. Finally, it drops the dependency on regex in favor
of using regex-syntax and regex-automata directly.
The top-level listing was just getting a bit too long for my taste. So
put all of the code in one directory and shrink the large top-level mess
to a small top-level mess.
NOTE: This commit only contains renames. The subsequent commit will
actually make ripgrep build again. We do it this way with the naive hope
that this will make it easier for git history to track the renames.
Sigh.
