jsonlint coalesce.json in prep for refactor
Sometimes you need to get slower to get faster.

Refactors phrasematch/coalescezooms such that coalesced stacks are not arrays of pointers to feature relev objects but use a feature tmpid instead.
Performance: use a bitmask for tracking contributing terms.
Simplify coalesce function args.
No features arg either.
Use cxx implementation of coalesceZooms
Exclude features with negative scores from context results.
Compare scores across indexes.
Merge pull request #188 from mapbox/context-score-fix

Exclude features with negative scores from context results
1.4.3
Merge branch 'master' into score-crossindex
Add test for cross-index scoring.
Utilize _sort strategically in verifymatch stage.
Merge pull request #189 from mapbox/score-crossindex

[semver bump] Compare scores across indexes
1.5.0
Merge branch 'master' into big-pants-rslow
Use async coalesceZooms
Merge branch 'querymask' into big-pants-rslow
Reduce selrelevance even further.
Update bench.