Upgrade to Mapnik new geometry

[springmeyer]

Huge progress in Mapnik's mapnik-geometry branch on a new storage for geometries: mapnik/mapnik#2739

This is close to merging and we should plan a node-mapnik 3.3.x series around it.

Steps to get this done:

• mapnik-vector-tile updated to compile with [wip] Mapnik geometry mapbox/mapnik-vector-tile#94
• node-mapnik updated to compile with [wip] Port to Mapnik new geometry storage #428
• more fully featured node-mapnik geometry API

[springmeyer]

d451454 gets a branch going of node-mapnik that disables all the spots that don't compile yet. It is segfaulting for unknown reasons when running the tests. /cc @flippmoke. Next actions:

• @springmeyer sprints on finishing mapnik-vector-tile port: Upgrade to new mapnik geometry storage mapbox/mapnik-vector-tile#93
• @flippmoke starts porting node-mapnik where possible (starting with parts that don't depend on mapnik-vector-tile)

[springmeyer]

done in #428