Floating Island World Generation

Major changes:

• Added custom ore creation

Minor changes:

• Added nether quartz and glowstone to the list of removable blocks
  
• Added glowstone ore veins to nether islands
  
• Only nether quartz and glowstone veins will be on nether islands
  
• Added config setting for glowstone vein rarity
  
• No ores spawn on ender islands (unless custom ones added for it)
  
• Nether quartz and glowstone veins can generate into the air

Using a parent generator is subject to bugs out of my control, such as the parent generator affecting the placed islands or crashes because of incompatibility. Known issues:
Fjord trees occasionally generate on the islands.
Server crashes when using 173generator (not sure if up to date).