use classes for octave application and interpreter * main-cli.cc (main): Simplify using class objects. * main-gui.cc (main): Likeiwse. * octave.h, octave.cc (octave::cmdline_options, octave::application, octave::cli_application, octave::embedded_application, octave::interpreter): New classes. Replace ordinary functions and static/global data with objects. Access global application data through application object. * octave-gui.h, octave-gui.cc (octave::gui_application): New class. Replace ordinary functions and static/global data with objects. * main-window.cc (main_window::m_app_context): New data member. (main_window::main_window): Pass application object instead of start_gui flag. (main_window::construct_octave_qt_link): Pass m_app_context to octave_qt_link constructor. * octave-interpreter.h, octave-interpreter.cc (octave_interpreter::m_app_context, octave_interpreter::m_exit_status): New data members. (octave_interpreter::execute): Use class object to start interpreter. Save exit status. * octave-qt-link.h, octave-qt-link.cc (octave_qt_link::m_app_context): New data member. (octave_qt_link::do_set_default_prompts): Make prompt settings conditional on whether the GUI is running. * input.h, input.cc (interactive, forced_interactive): Delete global data. * dirfns.cc, error.cc, input.cc, oct-stream.cc, pager.cc, sighandlers.cc, sysdep.cc, toplev.cc, lex.ll: Access interactive and forced_interactive through global application object.

--- a/libinterp/parse-tree/lex.ll	Mon Jul 11 13:45:12 2016 -0400
+++ b/libinterp/parse-tree/lex.ll	Sun Jul 10 07:15:21 2016 -0400
@@ -107,6 +107,7 @@
 #include "errwarn.h"
 #include "input.h"
 #include "lex.h"
+#include "octave.h"
 #include "ov.h"
 #include "parse.h"
 #include "pt-all.h"
@@ -2321,7 +2322,7 @@
   // input.
 
   if (! quitting_gracefully
-      && interactive
+      && octave::application::interactive ()
       && ! (reading_fcn_file
             || reading_classdef_file
             || reading_script_file