add two basic garbage cleaners
Merge remote-tracking branch 'origin/garbage' into collect
faster loops, more accurate
attempted tests
update tests to not reencode but compare json instead
us vt.parse() to test garbage collected tiles
add cleaner to index.js, update test fixtures
little improvements
add benchmarks for garbage collection
fix benchmark tests
more benchmarks and data for plotting
add another simplified cleaner, improve benchmarks
add comment
clean up features eaten by group by
Merge remote-tracking branch 'origin/garbage' into collect