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 pre- and post-quantization split.
Checkpoint post-quantization.