handle float attribute in mapnik vector tile
Merge pull request #184 from halset/float-vector-attribute

float attribute in mapnik vector tile
Added support for Mapnik tiles in mbtiles files.  A few fixes for ETC2/EAC.
Merge
Updated to new AFNetworking. Fixed a locking problem in the layout manager.
Documentation fixes.
Update to new AFNetworking.  Fixed MBTiles bug.
Wasn't correctly selecting triangle meshes.  Added selectibility option for vector tiles.
Merge branch 'develop' of https://github.com/mousebird/WhirlyGlobe into develop