Java Edition 15w34b

15w34b was released to fix some bugs and crashes from 15w34a.

Changes

 * All mobs
 * Give off brown hearts when hurt.
 * Will give off more of these particles when more damage is done to them.
 * Command blocks
 * Improved handling of flow with failing commands.
 * 2 new settings - Unconditional and Conditional.
 * Defaults to unconditional.
 * When conditional is set, it will only execute when the command block behind it was successful in execution.
 * Now supports tab auto-completion.
 * Combat
 * New 'Attack Speed' attribute, generic.attackSpeed, measuring fully-charged attacks per second. Base is 4.0, meaning the bar refills in 0.25s.
 * Swords, pickaxes, and shovels have a modifier of -2.75, resulting in a value of 1.25 (bar refilling in 0.8s).
 * Axes have a modifier of -3.2, resulting in a value of 0.8 (bar refilling in 1.25s).
 * The Haste effect increases the attack speed, while Mining Fatigue decreases it.
 * Armor points now depend on armor durability.
 * When armor reaches half durability, armor points will go to 1 (half an armor bar). This is probably a bug, see.
 * Minecarts with command blocks
 * Now have the new impulse command block texture.