Add split_to_tiles.sql, for splitting polys to tiles.
Add split_to_tiles.sql, for splitting polys to tiles.

data/split_to_tiles.sql
	-This SQL file exports a function, `mz_SplitIntoTiles()`, that
	can be used to split a table of polygons into a gridded table of
	tiles.

gronke/vector-datasource,adncentral/vector-datasource,zoondka/vector-datasource,gronke/vector-datasource,adncentral/vector-datasource,kyroskoh/vector-datasource,mapzen/vector-datasource,adncentral/vector-datasource,zoondka/vector-datasource,mapzen/vector-datasource,adncentral/vector-datasource,kyroskoh/vector-datasource,mapzen/vector-datasource