* the old cursor is stored before dispatch and then used after moving

* the old cursor is stored before dispatch and then used after moving
  up/down to tell the insets that the cursor left them. The
  notifyCursorLeaves methods can set updateFlags to trigger a redraw.
* leave mathed with cursor up/down and get the math redrawn for the
  decorations

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@18773 a592a061-630c-0410-9148-cb99ea01b6c8