[ardour-dev] latest CVS commit

[Paul Davis]

   * move doi.h to libs/gtkmmext/gtkmmext
   * add new MessageWithConfirmation object to libgtkmmext
   * fix crash in handling DiskOverrun or DiskUnderrun messages
   * various mouse binding fixes and cleanups from Gerard
   * added Route::silent_roll() to be used when slaving and not
       locked.
   * correct region fade in/fade out curves after split

   * libgtkmmext: 6.3.0
     libardour: 0.840.0
     ardour/gtk: 0.537.0