* Some more clever elide mode for the LyX buffer tabs. In trunk

* Some more clever elide mode for the LyX buffer tabs. In trunk
  currently the whole path is (possibly with some unmotivated ... in
  the middle) used which is usually far too long.

  The algorithm implemented here will start with absolute paths. From
  left to right path segments are added to the display string if they
  help to make the display strings more unique. Otherwise nothing is
  added, or if some middle path segments are omitted otherwise, three
  dots ... are used.

  The result is that we get just the base filename without extension if
  they are unique in the tabbar.

  The patch is open for discussion. If there is demand we can create
  yet another preference option to get back the old behaviour.

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@24555 a592a061-630c-0410-9148-cb99ea01b6c8