Track which player "owns" a turtle

When a player places a turtle, they are marked as its owner. Any actions
they perform (such as breaking blocks, moving, etc...) are performed
using this player's game profile.

This allows turtles to work correctly with various permissions mods.
Previously you would have to whitelist all turtles in order for them to
function within a claim.

src/main/java/dan200/computercraft/api/turtle/ITurtleAccess.java

@@ -6,6 +6,7 @@
 
 package dan200.computercraft.api.turtle;
 
+import com.mojang.authlib.GameProfile;
 import dan200.computercraft.api.lua.ILuaContext;
 import dan200.computercraft.api.lua.LuaException;
 import dan200.computercraft.api.peripheral.IPeripheral;
@@ -135,6 +136,14 @@ public interface ITurtleAccess
      */
     int getColour();
 
+    /**
+     * Get the player who owns this turtle, namely whoever placed it.
+     *
+     * @return This turtle's owner.
+     */
+    @Nonnull
+    GameProfile getOwningPlayer();
+
     /**
      * Get the inventory of this turtle
      *
@@ -148,7 +157,7 @@ public interface ITurtleAccess
      * Get the inventory of this turtle as an {@link IItemHandlerModifiable}.
      *
      * @return This turtle's inventory
-     * @see #getInventory() 
+     * @see #getInventory()
      * @see IItemHandlerModifiable
      * @see net.minecraftforge.items.CapabilityItemHandler#ITEM_HANDLER_CAPABILITY
      */