[MC-56365] Cloud shows through slime block

Clouds visible through slime blocks: see screenshot

Environment

Java version
1.7.0_55
OS name
Windows 8.1
OS version
6.3

Duplicate of MC-9553. Slime blocks are transparent, and there's a known issue with clouds rendering over transparent blocks.

At least everything doesn't show in front of water anymore... that was annoying.

As 2014-06-06_22.50.54.png shows, this can create unusual behaviour.