Java Edition 1.8.1-pre4

1.8.1-pre4 is the fourth pre-release for 1.8.1.

Changes

 * Performance
 * Many optimizations.
 * Options
 * Off/fancy/fast clouds.
 * Off/on entity shadows.
 * Fast/fancy now only controls leaves and rain particles.
 * Dropped items
 * On fast graphics, they now rotate.