Removing locks for eligible_fns_cache because we don't access it in a multithreaded manner.
Inconsequential whitespace fix.
Correctly handle incremental search.

If our input string stays the same but we've got more files found by the candidate thread, add to our existing results without wiping them out.
Prefer files nested as shallowly as possible.
Fixing tests.
Print a search status with our incremental search.  Decrease screen refresh time to 80ms.
Merge branch 'incremental_search'