Sketch of vtile.query functionality.
Merge branch 'master' into vtile-query
i, not 0.
z is relevant.
Bad z.
Nuke xray interactivity feature, query is better.
Use mapnik ~1.4.3.
Update query results to reflect mapnik 1.4.3.
Merge pull request #54 from mapbox/vtile-query

queryTile functionality