Bukkit

• added preventZeroOutput option to config.
  If turned to false, items will be used up even if they yield no output.
  This prevents furnaces from beeing stuck with unsmeltable items, wasting lots of fuel.
• changed the default config file to add way more default recipes
• fixed some possible bugs
• code cleanup ;)

A huge thank you at RabidFX for providing the preventZeroOutput option and some bug fixes! :)