Adding optional clipping to tippecanoe-overzoom (#298)

* Plumb a clip bounding box around through overzoom

* Actually do some clipping

* Add a test

* Fix post-binning clipping

* Factoring out geometry parsing from feature parsing

* Accept a clip polygon argument to tippecanoe-overzoom

* Progress in the direction of polygon clipping

* Fix the wagyu flags. We need intersection, not union

* Remove debug spew

* Clip points to polygon bounds too

* Copy the geometric binning code to serve as intersection-finding code

* Add clipper2 for linestring clipping

* Compiles, but does not actually seem to clip. Hmm.

* Oh, it helps if I actually call the function

* Add clipping tests

* Add missing fixture, and don't crash if it is missing

* Remember to do polygon clipping after binning too

* Fix scaling before post-binning clipping. Add test.

* Remove unused parts of clipper

* Rename for consistency

* Revert accidentally added line

* Clip the clip regions to the tile bounds to reduce their complexity

* Add a test of clipping the clip region down to the tile boundary

* Update version and changelog

geojson.cpp

@@ -199,7 +199,7 @@ int serialize_geojson_feature(struct serialization_state *sst, json_object *geom
 	}
 
 	drawvec dv;
-	parse_geometry(t, coordinates, dv, VT_MOVETO, sst->fname, sst->line, feature);
+	parse_coordinates(t, coordinates, dv, VT_MOVETO, sst->fname, sst->line, feature);
 
 	serial_feature sf;
 	sf.layer = layer;