* Reduce maxzooms being guessed a little:
* Use 1.5 standard deviations, not 2, as the minimum distinguishable
* Give overlapping polygons and linestrings more distinct indices
* Add another drop rate guessing options, from the same metrics -zg uses
* Guard against using -rp without -zg
* Handle points too when dropping or coalescing the "smallest" features.
* Add statistics of tile size reduction strategies to tileset metadata
* Update changelog and version
* Update documentation
The first feature in a tile can never be dropped, since there is
no previous feature to attach its properties to.
Remove the previous special case that reset the dropping counter
at the first feature within each tile proper (as opposed to the
first feature in each tile, including its buffer, which is now
the one that is guaranteed to be preserved).
Erica Fischer