Fix PotionEffect removal.

The method in EntityLiving to remove a potion effect was remapped during
the 1.7.5 update.  The method invocation in CraftLivingEntity was not
updated to invoke the remapped method, which has led to a random method in
LivingEntity being called in its place.

This commit corrects the behavior of removePotionEffect by changing the
method to invoke the remapped method as opposed to EntityLiving#m(float).

Thanks to @gabizou for finding this issue.

src/main/java/org/bukkit/craftbukkit/entity/CraftLivingEntity.java

@@ -280,7 +280,7 @@ public class CraftLivingEntity extends CraftEntity implements LivingEntity {
     }
 
     public void removePotionEffect(PotionEffectType type) {
-        getHandle().m(type.getId()); // Should be removeEffect.
+        getHandle().removeEffect(type.getId());
     }
 
     public Collection<PotionEffect> getActivePotionEffects() {