Add <e@entity.silent> tag and dEntity.silent mech

- spawn ender_dragon[has_ai=false;silent=true] l@1,2,3,world
Silent, non-wing-flapping ender dragon. Yay

src/main/java/net/aufdemrand/denizen/Denizen.java

@@ -769,6 +769,7 @@ public void onEnable() {
             propertyParser.registerProperty(EntityPowered.class, dEntity.class);
             propertyParser.registerProperty(EntityProfession.class, dEntity.class);
             propertyParser.registerProperty(EntityRotation.class, dEntity.class);
+            propertyParser.registerProperty(EntitySilent.class, dEntity.class);
             propertyParser.registerProperty(EntitySitting.class, dEntity.class);
             propertyParser.registerProperty(EntitySize.class, dEntity.class);
             propertyParser.registerProperty(EntitySkeleton.class, dEntity.class);

src/main/java/net/aufdemrand/denizen/objects/properties/entity/EntitySilent.java

@@ -0,0 +1,97 @@
+package net.aufdemrand.denizen.objects.properties.entity;
+
+import net.aufdemrand.denizen.objects.dEntity;
+import net.aufdemrand.denizencore.objects.Element;
+import net.aufdemrand.denizencore.objects.Mechanism;
+import net.aufdemrand.denizencore.objects.dObject;
+import net.aufdemrand.denizencore.objects.properties.Property;
+import net.aufdemrand.denizencore.tags.Attribute;
+import org.bukkit.craftbukkit.v1_8_R3.entity.CraftEntity;
+import org.bukkit.entity.Entity;
+
+public class EntitySilent implements Property {
+
+    public static boolean describes(dObject entity) {
+        return entity instanceof dEntity;
+    }
+
+    public static EntitySilent getFrom(dObject entity) {
+        if (!describes(entity)) return null;
+        else return new EntitySilent((dEntity) entity);
+    }
+
+
+    ///////////////////
+    // Instance Fields and Methods
+    /////////////
+
+    private EntitySilent(dEntity ent) {
+        entity = ent;
+    }
+
+    dEntity entity;
+
+    /////////
+    // Property Methods
+    ///////
+
+    @Override
+    public String getPropertyString() {
+        return String.valueOf(isSilent(entity.getBukkitEntity()));
+    }
+
+    @Override
+    public String getPropertyId() {
+        return "silent";
+    }
+
+
+    ///////////
+    // dObject Attributes
+    ////////
+
+    @Override
+    public String getAttribute(Attribute attribute) {
+
+        if (attribute == null) return "null";
+
+        // <--[tag]
+        // @attribute <e@entity.silent>
+        // @returns Element(Boolean)
+        // @group attributes
+        // @description
+        // Returns whether the entity is silent. (Plays no sounds)
+        // -->
+        if (attribute.startsWith("silent"))
+            return new Element(isSilent(entity.getBukkitEntity()))
+                    .getAttribute(attribute.fulfill(1));
+
+
+        return null;
+    }
+
+    @Override
+    public void adjust(Mechanism mechanism) {
+
+        // <--[mechanism]
+        // @object dEntity
+        // @name silent
+        // @input Element(Boolean)
+        // @description
+        // Sets whether this entity is silent. (Plays no sounds)
+        // @tags
+        // <e@entity.silent>
+        // -->
+        if (mechanism.matches("silent") && mechanism.requireBoolean()) {
+            setSilent(entity.getBukkitEntity(), mechanism.getValue().asBoolean());
+        }
+    }
+
+    private static boolean isSilent(Entity entity) {
+        return ((CraftEntity) entity).getHandle().R();
+    }
+
+    private static void setSilent(Entity entity, boolean silent) {
+        ((CraftEntity) entity).getHandle().b(silent);
+    }
+}