Add dPlayer.edit_sign mech

I love packets

src/main/java/net/aufdemrand/denizen/objects/dPlayer.java

@@ -2221,6 +2221,18 @@ else if (split.length > 1) {
             OpenBook.openBook(getPlayerEntity());
         }
 
+        // <--[mechanism]
+        // @object dPlayer
+        // @name edit_sign
+        // @input dLocation
+        // @description
+        // Allows the player to edit an existing sign. To create a
+        // sign, see <@link command Sign>.
+        // -->
+        if (mechanism.matches("edit_sign") && mechanism.requireObject(dLocation.class)) {
+            SignEditor.editSign(getPlayerEntity(), value.asType(dLocation.class));
+        }
+
         // Iterate through this object's properties' mechanisms
         for (Property property : PropertyParser.getProperties(this)) {
             property.adjust(mechanism);

src/main/java/net/aufdemrand/denizen/utilities/packets/SignEditor.java

@@ -0,0 +1,47 @@
+package net.aufdemrand.denizen.utilities.packets;
+
+import net.aufdemrand.denizen.utilities.debugging.dB;
+import net.minecraft.server.v1_8_R1.BlockPosition;
+import net.minecraft.server.v1_8_R1.PacketPlayOutOpenSignEditor;
+import net.minecraft.server.v1_8_R1.TileEntity;
+import net.minecraft.server.v1_8_R1.TileEntitySign;
+import org.bukkit.Location;
+import org.bukkit.craftbukkit.v1_8_R1.CraftWorld;
+import org.bukkit.entity.Player;
+
+import java.lang.reflect.Field;
+import java.util.Map;
+
+public class SignEditor {
+
+    private static final Field sign_location;
+
+    static {
+        Map<String, Field> fields = PacketHelper.registerFields(PacketPlayOutOpenSignEditor.class);
+        sign_location = fields.get("a");
+    }
+
+    public static PacketPlayOutOpenSignEditor getSignEditorPacket(Location location) {
+        PacketPlayOutOpenSignEditor signEditorPacket = new PacketPlayOutOpenSignEditor();
+        try {
+            sign_location.set(signEditorPacket, new BlockPosition(location.getX(), location.getY(), location.getZ()));
+        } catch (Exception e) {
+            dB.echoError(e);
+        }
+        return signEditorPacket;
+    }
+
+    public static void editSign(Player player, Location location) {
+        PacketPlayOutOpenSignEditor signEditorPacket = getSignEditorPacket(location);
+        TileEntity sign = ((CraftWorld) location.getWorld()).getTileEntityAt(location.getBlockX(),
+                location.getBlockY(), location.getBlockZ());
+        if (sign instanceof TileEntitySign) {
+            ((TileEntitySign) sign).isEditable = true;
+            PacketHelper.sendPacket(player, signEditorPacket);
+        }
+        else {
+            dB.echoError("Can't edit non-sign materials!");
+        }
+    }
+
+}