Fixed the half-done hunger implementation, fixed lots of bugs related to hunger

- Fixed starvation doesn't deal any damage at all (Human->getFood() returns a float, not an int, === 0 won't work so great)
- Added exhaustion for sprinting, walking, jumping and sprint-jumping as per MCPE (these use MCPE values, and yes MCPE does walking exhaustion!)
- Fixed attributes don't get reset after player death
- Added food and hunger regeneration in peaceful difficulty
- Added API methods Living->jump() (motion isn't updated yet, so this won't actually do much if plugins try to use it) and Living->getJumpVelocity()

TODO: implement exhaustion for swimming

src/pocketmine/entity/Living.php

@@ -43,6 +43,8 @@ abstract class Living extends Entity implements Damageable{
 
 	protected $invisible = false;
 
+	protected $jumpVelocity = 0.42;
+
 	protected function initEntity(){
 		parent::initEntity();
 
@@ -115,6 +117,23 @@ abstract class Living extends Entity implements Damageable{
 		$this->attackTime = 0;
 	}
 
+	/**
+	 * Returns the initial upwards velocity of a jumping entity in blocks/tick, including additional velocity due to effects.
+	 * @return float
+	 */
+	public function getJumpVelocity() : float{
+		return $this->jumpVelocity + ($this->hasEffect(Effect::JUMP) ? (($this->getEffect(Effect::JUMP)->getAmplifier() + 1) / 10) : 0);
+	}
+
+	/**
+	 * Called when the entity jumps from the ground. This method adds upwards velocity to the entity.
+	 */
+	public function jump(){
+		if($this->onGround){
+			$this->motionY = $this->getJumpVelocity(); //Y motion should already be 0 if we're jumping from the ground.
+		}
+	}
+
 	public function attack($damage, EntityDamageEvent $source){
 		if($this->attackTime > 0 or $this->noDamageTicks > 0){
 			$lastCause = $this->getLastDamageCause();
@@ -183,6 +202,10 @@ abstract class Living extends Entity implements Damageable{
 			return;
 		}
 		parent::kill();
+		$this->callDeathEvent();
+	}
+
+	protected function callDeathEvent(){
 		$this->server->getPluginManager()->callEvent($ev = new EntityDeathEvent($this, $this->getDrops()));
 		foreach($ev->getDrops() as $item){
 			$this->getLevel()->dropItem($this, $item);