Add d3.zip target.

Author: mbostock

Makefile

@@ -14,6 +14,9 @@ test:
 src/start.js: package.json bin/start
 	bin/start > $@
 
+d3.zip: LICENSE d3.js d3.min.js
+	zip $@ $^
+
 d3.js: $(shell node_modules/.bin/smash --ignore-missing --list src/d3.js) package.json
 	@rm -f $@
 	node_modules/.bin/smash src/d3.js | node_modules/.bin/uglifyjs - -b indent-level=2 -o $@