o Added user_data() to Fl_Tree_Item
o Added insert() and add() methods that allow specification of Fl_Tree_Prefs
o Changed Fl_Pixmap args to Fl_Image for more flexibility
o Fixes for positioning of items in the presence of user icons
o find_children() changed from protected -> public
git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3@6956 ea41ed52-d2ee-0310-a9c1-e6b18d33e121
