changes to qt graphics initialization

[John W. Eaton]

Heads up for anyone building the default branch, I just pushed a couple 
of changesets that reorganize the way qt graphics are linked and 
initialized:

  http://hg.savannah.gnu.org/hgweb/octave/rev/028205a91a07
  http://hg.savannah.gnu.org/hgweb/octave/rev/2ff12b707f60

After updating your sources, you'll probably need to delete the 
libgui/graphics directory in your build tree to make the build work 
properly again.

jwe