Checkpoint pre- and post-quantization split.
Checkpoint post-quantization.
Working post-quantization!
Better error check.
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.
Don’t skip collapsed arc segments.

Removing collapsed arc segments still affects the topology, because a zero-
length arc segment can still affect whether two features are connected.
Fix prune test.
Remove coincident points after simplifying.

Also guarantee that post-quantized arcs have at least two points, per the
TopoJSON specification.
Merge branch 'pre-post-quantize' into merge
Update us-10m.json.