Support feature ids. Improve error reports. Fix a misspelling.

• Clean up parsing and serialization. Provide some context with parsing errors.
• Fix the spelling of the --preserve-input-order option
• Support the "id" field of GeoJSON objects and vector tile features
• Fix error reports when reading from an empty file with parallel input

Variable simplification, and an empty-geometry fix

• Add an option to vary the level of line and polygon simplification
• Be careful not to produce an empty tile if there was a feature with empty geometry.
• Be even more careful not to produce features with empty geometry

Tile layer version, projected decoding, and progress indicator fixes

• Fix double-counted progress in the progress indicator
• Add ability to specify a projection to tippecanoe-decode
• Fix incorrect tile layer version numbers in tile-join output

Minimal alternate projection support, point glow, tile-join -x fix

• Fix a tile-join bug that would retain fields that were supposed to be excluded
• Add minimal support for alternate input projections (EPSG:3857).
• Add an option to calculate the density of features as a feature attribute

Memory crunching, buffering, polygon decoding

• Keep metadata together with geometry for features that don't span many tiles, to avoid extra memory load from indexing into a separate metadata file
• Reduce the size of critical data structures to reduce dynamic memory use
• Let zoom level 0 have just as much extent and buffer as any other zoom
• Fix tippecanoe-decode bug that would sometimes show outer rings as inner

More polygon fixes and code cleanups

• Don't let polygons with nonzero area disappear during cleaning
• Internal code cleanup
• Update Clipper to fix potential crash
• Make better use of C++ standard libraries

Convert C source files to C++

• Convert C source files to C++

Upgrade Clipper to fix potential crashes and improve polygon topology

• Upgrade Clipper to fix potential crashes and improve polygon topology

Switch to protozero as the library for reading and writing protocol buffers

• Switch to protozero as the library for reading and writing protocol buffers

Add an option not to clip features

• Add option not to clip features
• Clean up polygons after coalescing, if necessary