Provide onboard optimizations for strings with similar prefixes and suffixes in PhutilEditDistanceMatrix
Summary: We can evaluate similar prefixes and suffixes in O(1). Provide this optimization within PhutilEditDistanceMatrix.
Test Plan: Ran unit tests.
Reviewers: btrahan, Afaque_Hussain
Reviewed By: btrahan
CC: aran
Maniphest Tasks: T2379
Differential Revision: https://secure.phabricator.com/D6014