Do more of line simplification with integer coordinates (#113)

* Turn off unit, which has bit-rotted

* Instrument line simplification

* Do more work in integer space

* Update tests with simplification done with more integers

* Clean up

* Update changelog

* Eradicate calls to deprecated sprintf()

* Revert "Turn off unit, which has bit-rotted"

This reverts commit 998779313f.

* Fix catch by switching to an unsigned type

read_json.cpp

@@ -45,7 +45,7 @@ void json_context(json_object *j) {
 	char *s = json_stringify(j);
 
 	if (strlen(s) >= 500) {
-		sprintf(s + 497, "...");
+		snprintf(s + 497, strlen(s) + 1 - 497, "...");
 	}
 
 	fprintf(stderr, "in JSON object %s\n", s);