Java Edition Alpha v1.0.13

Alpha 1.0.13 was mainly released to fix bugs and work towards a SMP release.

Changes

 * Slimes have new look
 * The client now checks if two instances of the game try to save to the same level, and quits if it does.
 * The SMP join screen now has random passwords shown in the password box.
 * More work on SMP

Fixes
1 bug fixed


 * Fixed a hang/crash bug related to lighting.