Round coordinates instead of truncating them (#60)

* Round coordinates instead of truncating them

* Update all the tests for coordinate rounding changes

* Curses, integer division still truncates

* Fix tests

* Also round instead of shifting when looking for no-op linetos

* Should I worry that the same change for moveto doesn't change any tests?

* Also round instead of shifting when scaling down to maxzoom resolution

* Replace another explicit shift, for origin point

* Round instead of shift when writing clipped geometries to the next zoom

* Fix low-zoom gridding and smaller-than-a-pixel checks

* Don't guess an excessively large maxzoom when there is only one feature

* Add a test for guessing the maxzoom of a single point

* Explicitly sort by index if no other order distinguishes features

* Another affected test

CHANGELOG.md

@@ -1,3 +1,7 @@
+## 2.20.0
+
+* Round coordinates instead of truncating them, for better precision when overzooming
+
 ## 2.19.0
 
 * Don't guess an excessively large maxzoom when there is only one feature