Add "update" option to the Inventory command

Only player inventories can be 'updated' at the moment, but it's still
something needed.
Fix dLocation constructor error
Add <n@npc.has_pose[<name>]> and <n@npc.get_pose[<name>]>; Fix some tag meta

<n@npc.get_pose[<name>]> will return the pitch and yaw of the pose
(that's all that's given)... x, y, and z are all defaulted to 0 and the
world is just the first world Bukkit picks up.
Update Pose to 0.9, add some new options

You can now add and remove NPC poses.