Implement skeletton for WaypointMovement by id

Main Goal:

Unify waypoint handling between guid-waypoints, entry-waypoints, additional paths assigned uniquely to summoned mobs and waypoints assigned via SD2

Ideas:
* merge creature_movement and creature_movement_template into one table.
  Any idea for this would be welcome

Also i suggest to add the possibiilty to store paths (entry, someCustomIdForThePath) in this same table to be able to ie let a mob start way X on quest A, and way Y on quest B
( COMMAND_START_MOVEMENT(waypoint, X) for A and
  COMMAND_START_MOVMEENT(waypoint, Y) for B     )

Currently done:
* Also improve a bit default behaviour for WaypointMMGen
* Add new storage for WaypointPath of NpcEntry, id to WaypointMgr
* Add wrappers to load paths by npcEntry, id to WaypointMgr
* Change MotionMaster::MoveWaypoint to be able to select a path

TODO:
* TODO: Well, load content to the new storage
* TODO: Add wrappers to actually use the new paths

* TODO: To be really usefull, this will require ways a rewrite of MotionMaster to keep WaypointMovement that was stacked also after evade..

* TODO: Figure how to store more content
* TODO: Figure also how to assign summoning and individual path (COMMAND_SUMMON_WITH_PATH ?)