Stitch across [Multi]Polygon rings.

Previously, fragments would only be stitched for individual rings.
Preserve polygon when stitching MultiPolygons.

Rings that don't need stitching should stay in their respective
polygons.
Implement suggested restructuring.
Checkpoint pre- and post-quantization split.
Checkpoint post-quantization.
Working post-quantization!
Better error check.
Checkpoint topojson.merge.

I don’t really like exposing topojson.arcmesh.
Somewhat-functional merge implementation.

Because of the necessary point-in-polygon check to reconstruct polygon systems
after merging, this implementation currently assumes Cartesian coordinates.
However, in many cases the coordinate system should not have any effect on
merging, so I’m hoping this isn’t too severe of an initial limitation.

Also, fix two bugs in topojson.mesh: the `start` and `end` temporaries on each
arc weren’t being cleaned up after the mesh was constructed, and we were
assuming delta encoding rather than checking for a transform.
Don’t export the geojson binary.
Add topojson-merge.
topojson.arcmesh: preserve arc directions.

The information about the direction of each arc used in each geometry is
preserved, so that it can be used as a hint when constructing the mesh.
Export topojson-merge.
Restore quantize rounding.

A better way to avoid aliasing issues is to ensure that during pre-quantization,
the fine quantization grid is aligned with the ultimate post-quantization grid.
Fix error.
Fix quantization logging for Cartesian coordinates.
Remove dead code.
Simplify topojson.mesh; move topojson.merge.

Move merge to the TopoJSON client API. Rewrite mesh so that it is guaranteed to
preserve winding order of arcs (and output any leftover arcs that couldn’t be
stitched together).

Simplify the merge API: it is now just merge(geometries) where geometries is an
array of Polygon or MultiPolygon geometry objects. We could probably do
something like have merge(topology, geometries) return GeoJSON rather than
TopoJSON, for consistency with mesh(topology, object). I thought it was simpler
to have merge take an array of geometries, but I might also consider having it
take a GeometryCollection for consistency with mesh.

This commit also breaks the merge implementation, but I’m planning on rewriting
that next to preserve polygon semantics (hole-ring relationships).
Somewhat functioning implementation.
Fix for holes.

We must consider holes when computing connected components because one polygon
may completely surround another polygon. In the end, this is also simpler
because stitching preserves winding orders, so once we have determined the
connected components we don’t need to do anything else to preserve holes!