refactor and rewrite, many bug fixes, optional indicator sprites, real version bump

Author: sparr

Diff for: config.lua

@@ -2,3 +2,6 @@ require 'defines'
 
 -- times per second (max 60) that belts will be checked for overflow
 belt_polling_rate = 60
+
+-- draw a red box on belts that can overflow
+draw_terminal_indicator = true