Update CraftBukkit to Minecraft 1.4.6
Filter invalid ItemStacks from Packets.

Invalid ItemStacks are causing Fireworks to disconnect players and
prevent them from reconnecting
[Bleeding] Fix exception in getChunkSnapshot() - sky light can be null
Fetch correct info for skulls in block.getDrops(). Fixes BUKKIT-3205
Remove obsolete fix for the end

The end was getting block offsets, causing client side issues.
Add the ability to make Enchanted Books. Fixes BUKKIT-3220
Add API to allow plugins to request players switch to a texture pack. Adds BUKKIT-2579

The setTexturePack method causes the player's client to
download and switch to a texture pack specified by a URL.

Note: Players can disable server textures on their client, in which
case this API would not affect them.
Implement 1.4.6 ItemMeta. Adds BUKKIT-3236, BUKKIT-3237

Some meta functionality is refactored into common methods.

CraftItemStack uses the ItemMetaKey identifiers for enchantments.

Refactored unit test to include extra functionality; initially only
checking the presence of the DelegateDeserialization annotation.
Use max inventory size for new stack. Fixes BUKKIT-3240
Add a null check for Item Entities. Fixes BUKKIT-3249
Fix command line arguments being ignored. Fixes BUKKIT-3247
Don't save server properties when it's read only. Fixes BUKKIT-3250
Fix loading Items entities with an invalid item. Addresses BUKKIT-3249
Update enchantment handling to 1.4.6. Fixes BUKKIT-3256
Check file existence before determining readOnly. Fixes BUKKIT-3255
Zero is not less than zero. Fixes BUKKIT-3259
Added TileEntitySkull for diff visibility
Implement Skull BlockState. Adds BUKKIT-3259
Implement API to get and set FireworkMeta on Firework entities
Updated version to 1.4.6-R0.1 in pom.xml for Beta.