Tippecanoe

* Further improvements to tile-join speed

* Improve speed of overzooming in tile-join

* Further reduce memory usage of --no-simplification-of-shared-nodes by calculating the list of shared nodes globally using temporary files rather than in memory for each individual tile
* Make --no-simplification-of-shared-nodes behave for LineStrings as it does for Polygons, preventing simplification only at crossings, convergences, and divergences, not at every point along collinear segments

* Reduce memory usage of --no-simplification-of-shared-nodes for polygons

* Extend --no-simplification-of-shared-nodes to also simplify shared polygon borders consistently

* Fix tile-join crash when trying to join empty tilesets
* Add --no-tiny-polygon-reduction-at-maximum-zoom option