Use faster method for calculating distances.

fix cmakelist

third_party/geometry.hpp-0.9.2/Makefile

@@ -0,0 +1,19 @@
+CXXFLAGS += -I include -std=c++14 -DDEBUG -O0 -Wall -Wextra -Werror
+MASON ?= .mason/mason
+
+VARIANT = 1.1.4
+
+default: test
+
+$(MASON):
+	git submodule update --init
+
+mason_packages/headers/variant/$(VARIANT):
+	$(MASON) install variant $(VARIANT)
+
+test: tests/* include/mapbox/geometry/* mason_packages/headers/variant/$(VARIANT) Makefile
+	$(CXX) tests/*.cpp $(CXXFLAGS) `$(MASON) cflags variant $(VARIANT)` -o test
+	./test
+
+clean:
+	rm -f test