v0.7.53

• Added gap-width= to -clean and -dissolve, for filling gaps narrower than a given distance (e.g. gap-width=2m). A gap's width is estimated from its area and perimeter, so slender cracks are filled while more compact holes of similar area, such as small lakes, are more likely to be kept. -clean now applies this width test by default, in place of the area test it used before; gap-fill-area= and sliver-control= are deprecated, but still accepted.
• Added -clean close-outer-gaps, which closes cracks that open onto the outside of a polygon mosaic, up to the width set by gap-width=, so that they are filled like enclosed gaps. It is opt-in because a narrow opening in a coverage is not always a mistake.
• Robustness and quality improvements in -buffer and -clean.
• Fixed TypeError: Cannot read properties of null when exporting FlatGeobuf with a precision= value that collapses a feature's geometry.
• Features with null geometry are now written to (and read back from) FlatGeobuf files as records with no geometry, matching what the GeoJSON and Shapefile exporters do.