Bukkit

Fixed dupe glitches with:

• Sand, red sand, gravel
• Double chests
• Beds

Cleaned up the code a bit to make future updates easier.

• Paintings and item frames will drop. This is not a bug because they aren't actual blocks (They are tile entities) so they won't be moved down.
• Blocks that don't have a valid spot to sit on will simply drop as an item including all contents in inventory. Not a bug though.
• Flower pots drop contents
• Sunflowers dupe