[ardour-dev] latest SVN commits

[Paul Davis]

  * do not save all of the undo history. 
       - this has been causing memory issues upon reload.
       - depth is now limited by a Configuration parameter
       - defaults to 100
       - no GUI editor for this parameter

  * new icons from thorsten

  * removed "orig_coordinates" debugging file

  * (BIG) use shared_ptr for all Playlist handling

  * "Cleanup" works again (more testing requested, use
      throwaway sessions)

  * rev 1210