Tippecanoe

* Adjust tile size limit with --retain-points-multiplier dynamically within each tile, to allow multiplier features at high zooms if other features are being dropped as-needed

* Add --unidecode-data option to allow case-insensitive filter comparisons of transliterated strings

* Change -fraction-as-needed feature dropping to be consistent across tiles and zoom levels, and to follow the same pattern as point dropping by zoom level
* With -as-needed feature dropping, drop or retain entire multiplier clusters instead of individual features
* Sort the features within each multiplier cluster by its retention priority, for more consistency between zoom levels in filtered feature choice

* Improve tiling speed
* Generate tilestats for the --retain-points-multiplier attributes

* Performance optimizations to tile reading, writing, and overzooming
* Automatically vary the tile size limit by zoom level to match the intended retain-points-multiplier multiplication
* Fix decompression error when bailing out because a tile can't be made small enough
* Search harder for a feature size threshold to make the tile small enough before giving up

* Add --accumulate-attribute to tippecanoe-overzoom
* Go back to ordering features within each multiplier cluster spatially, not in the order specified for tile feature order