Java Edition Alpha v1.2.1

Alpha 1.2.1 was mostly released to fix bugs.

Changes

 * Mob spawning reverted to old code.
 * Leaf particle colors now reflect the biome instead of the grayscale texture.

Fixes
4 bugs fixed


 * Signs on the sides of cacti no longer crash the game
 * Fixed the player getting stuck in the top of the world in SMP.
 * Optimized CPU usage for mob spawning
 * Music now plays in multiplayer