Bukkit

Minor-ish update:

• Added ender island, with obsidian towers and end portals
  
• Added config option to change how many caves are generated (default 1.0)
  
• Fixed a crash when islands generate below y=0 or above world height
  
• Changes to island generation code to make them more interesting
  
• Added quartz ore to nether islands
  
• Dungeons now remove sandstone when being placed