Oops, actually check attachment.
Better test.
Fix viewport scaling when not quantized.
Add --invert; fix scaling of non-quantized input.

When a --projection is specified, we assume that +y points down (as in SVG and
Canvas), and thus do not need to invert; however, then --projection is not
specified, we assume that +y points up (as in latitude).
Merge branch 'fix-filter-small-detached'
Fix for viewport scaling.

The transform scaling was assuming that the transform translate always pointed
to the smallest point in the bounding box, but that isn’t necessarily true.
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.