Removing Java dialog boxes. * scripts/gui/module.mk: removed message_dialog.m entry. * scripts/gui/private/message_dialog.m: merged code to msgbox. * scripts/gui/errordlg.m: function now redirects to msgbox. New tests. * scripts/gui/helpdlg.m: function now redirects to msgbox. New tests. * scripts/gui/warndlg.m: function now redirects to msgbox. New tests. * scripts/gui/msgbox.m: merged code from message_dialog. Stripped Java dialog boxes. New tests. * scripts/gui/inputdlg.m: stripped Java dialog boxes. Improved doc. New tests. * scripts/gui/listdlg.m: stripped Java dialog boxes. Improved doc. New tests. * scripts/gui/questdlg.m: stripped Java dialog boxes. Improved doc. New tests. * scripts/miscellaneous/menu.m: stripped Java dialog boxes. Improved doc. * scripts/java/module.mk: removed entries of deleted files. * scripts/java/org/octave/DlgListener.java: removed Java dialog box Listener. * scripts/java/org/octave/images/error.png: removed unused image. * scripts/java/org/octave/images/information.png: removed unused image. * scripts/java/org/octave/images/octave.png: removed unused image. * scripts/java/org/octave/images/question.png: removed unused image. * scripts/java/org/octave/images/warning.png: removed unused image. * scripts/java/org/octave/JDialogBox.java: removed Java dialog box class. * scripts/java/org/octave/TeXcode.java: removed class used by Java dialogs. * scripts/java/org/octave/TeXtranslator.java: removed class used by Java dialogs. * doc/module.mk: removed unused java images and java.txi. * doc/interpreter/java.txi: merged content as minor sections to following files. * doc/interpreter/bugs.txi: moved Java distinguish section here. * doc/interpreter/external.txi: moved Java Interface description here. * doc/interpreter/gui.txi: moved dialog box docstrings here. * doc/interpreter/octave.texi: corrected TOC. * doc/interpreter/java-images/image001.png: removed unused image. * doc/interpreter/java-images/image002.png: removed unused image. * doc/interpreter/java-images/image003.png: removed unused image. * doc/interpreter/java-images/image004.png: removed unused image. * doc/interpreter/java-images/image005.png: removed unused image. * doc/interpreter/java-images/image006.png: removed unused image. * doc/interpreter/java-images/image007.png: removed unused image. * doc/interpreter/java-images/image008.png: removed unused image. * doc/interpreter/java-images/image009.png: removed unused image. * NEWS: Announced changes.

--- a/NEWS	Tue Apr 19 12:30:18 2016 +0200
+++ b/NEWS	Tue Apr 19 15:27:19 2016 +0200
@@ -71,6 +71,10 @@
  ** The textscan function is now built-in and is much faster and much
     more Matlab-compatible than the previous m-file version.
 
+ ** Dialog boxes, errordlg, helpdlg, inputdlg, errordlg, listdlg,
+    msgbox, questdlg, and warndlg, now exclusively use QT.  Java based
+    versions are removed.
+
  ** Other new functions added in 4.2:
 
       deg2rad