Fix "strategies" accounting for 0-length linestrings and degenerate polygons (#137)

* Dropping a 0-length feature doesn't count as dropping-as-needed

* Add an option not to reduce tiny polygons to dust at maxzoom

* Add test for prevention of tiny polygon reduction at maxzoom

* Fix accounting for tiny polygons not to include degenerate geometries

* Revert "Add test for prevention of tiny polygon reduction at maxzoom"

This reverts commit f931bbd73e.

* Revert "Add an option not to reduce tiny polygons to dust at maxzoom"

This reverts commit 03f0882bb6.

* Fix tests

* Another test that no longer has any really tiny polygons

* Oops, that broke LineString simplification

* This time for sure!

* Update changelog and version

tests/curve/out/-z2.json

@@ -9,7 +9,6 @@
 "maxzoom": "2",
 "minzoom": "0",
 "name": "tests/curve/out/-z2.json.check.mbtiles",
-"strategies": "[{},{\"tiny_polygons\":1},{\"tiny_polygons\":4}]",
 "type": "overlay",
 "version": "2"
 }, "features": [

tests/curve/out/-z2_--no-clipping.json

@@ -9,7 +9,6 @@
 "maxzoom": "2",
 "minzoom": "0",
 "name": "tests/curve/out/-z2_--no-clipping.json.check.mbtiles",
-"strategies": "[{},{\"tiny_polygons\":1},{\"tiny_polygons\":10}]",
 "type": "overlay",
 "version": "2"
 }, "features": [

tests/curve/out/-z2_--no-duplication.json

@@ -9,7 +9,6 @@
 "maxzoom": "2",
 "minzoom": "0",
 "name": "tests/curve/out/-z2_--no-duplication.json.check.mbtiles",
-"strategies": "[{},{\"tiny_polygons\":6},{\"tiny_polygons\":6}]",
 "type": "overlay",
 "version": "2"
 }, "features": [