document tests and benchmarks
Fix russia fixture.
Assert that cover results match output fixtures and reformat output fixtures for smoother debugging.
Merge branch 'assert-output' into tile-scanline
Finish merge.
Let polygon covers get reduced.
Restore master versions of building, multiline fixtures.
Fix fixture output path.
Merge pull request #36 from mapbox/tile-scanline-test

[tile-scanline] Compare results vs fixture