Add preferences and prefdir functions * scripts/prefs/private/prefsfile.m (prefsfile): Use prefdir() instread of ~ for folder part of file. * scripts/prefs/preferences.m: New file. * scripts/prefs/prefdir.m: New file. * scripts/prefs/module.mk: Add preferences.m and prefdir.m * libinterp/corefcn/octave-link.h, libinterp/corefcn/octave-link.cc (octave_link::show_preferences): New function. (octave_link)::do_show_preferences: New fuction. (__octave_link_show_preferences__): New function. * libgui/src/octave-qt-link.h, libgui/src/octave-qt-link.cc (octave_qt_link::show_preferences_signal): New signal. (octave_qt_link::do_show_preferences): New function. * libgui/src/main-window.cc (main_window::construct_octave_qt_link): connect octave link to show settings dialog slot.

--- a/libgui/src/octave-qt-link.cc	Thu Jul 18 14:30:31 2013 -0400
+++ b/libgui/src/octave-qt-link.cc	Thu Jul 18 10:56:44 2013 -0400
@@ -491,3 +491,11 @@
 
   return ok;
 }
+
+void
+octave_qt_link::do_show_preferences ()
+{
+  emit show_preferences_signal ();
+}
+
+