Quotes turn off stemming.

Wrap something quotes to get a more specific match that also payes
attention to stop words.  This is a reimplementation of something in
MWSearch.

Unlike MWSearch you can turn stemming back on in a phrase search:
"foo bar"     - no stemming, matches stop words
"foo bar"~    - stemming and ignores stop words
"foo bar"~3   - no stemming, matches stop words, has a phrase slop of 3
"foo bar"~3~  - stemming and ignores stop words, has a phrase slop of 3

This change comes at a price: 54526.

Bug: 54020
Change-Id: I934c98d8245b2b52f9d432d71ef3f6adaa0c2bca
Merge "Quotes turn off stemming."