Guard against missing coordinates and excessive detail; allow point coalescing and Hilbert curve feature sequencing

1.32.9

• Limit tile detail to 30 and buffer size to 127 to prevent coordinate
  delta overflow in vector tiles.

1.32.8

• Better error message if the output tileset already exists

1.32.7

• Point features may now be coalesced into MultiPoint features with --coalesce.
• Add --hilbert option to put features in Hilbert Curve sequence

1.32.6

• Make it an error, not a warning, to have missing coordinates for a point