Tilequeue

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* Add command to dump the tiles of interest list to a text file
* Add support for generating metatiles (see also: tapalcatl)
* Add priority queues implementation
* Increase topojson scale from 1024 -> 4096

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* Add bbox filter to test for partial overlapping, rather than intersecting, the bbox.

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* Update wof projection to 3857.
* Update srid throughout from 900913 -> 3857.
* Add basic size logging for the objects returned from queries.
* Support multiple geometries in queries.
* Add filter to intersect with padded bounds.
* Conditionally store tile data. Print total storage counts for each tile.
* Correct the buffered mvt format definition.
* Convert wof min/max zooms to floats.
* Update sample cfg to reflect latest choices.
* Add pyclipper dependency to requirements.

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* Improve json encoding
* Add boroughs to wof processing
* Add support for configurable area thresholds
* Add l10n names to wof processing
* Port used TileStache fork code to eliminate dependency
* Add configurable bounds buffer support
* Remove simplification, now a vector-datasource transform step
* Ensure json properties are utf-8 encoded
* Add support to generate s3 urls with no path
* Handle empty strings when edtf parsing wof dates

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* Delegate quantization to mapbox-vector-tile. See [82](https://github.com/mapzen/tilequeue/issues/82).
* Expand mz_properties in features. See [81](https://github.com/mapzen/tilequeue/pull/81).
* Exclude null values from yaml output. See [84](https://github.com/mapzen/tilequeue/pull/84).
* Remove outdated tests exercising a transform that is no longer used. See [6de8f00](https://github.com/mapzen/tilequeue/commit/6de8f00579840794bdb7febd4e113a5cd976421a).

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* Use an empty list if the 'transforms' parameter is missing, rather than raise KeyError.
* Metatile at z16
* Support storing individual formatted layers
* Pass context object to post-process functions.
* Add resource abstraction to manage transforms with io requirements
* Don't filter out small features at z16, which may be needed for subsequent zooms