Fix #33674: Meta strip could overlap with other strips when exiting edit mode

Not sure what's the best thing to do here, for now just added vertical shuffle
of meta strip if it overlaps with other strips when existing edit mode.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@53574 954f8c5b-7b00-dc11-b283-0030488c597c