The terminal_panel in print.partynode was not applied to the root node
in case it was also the terminal node. A workaround has been added now.



git-svn-id: svn://svn.r-forge.r-project.org/svnroot/partykit@579 255f4249-2263-4417-b1ea-8498779e27a7
depth() generic is removed from partykit now, instead the generic from
grid is used -> dependency on at least 3.1.0.

NEWS and .Rd were also modified accordingly. In the .Rd I also made some
additional small touch-ups and improvements in the examples.



git-svn-id: svn://svn.r-forge.r-project.org/svnroot/partykit@580 255f4249-2263-4417-b1ea-8498779e27a7