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/corefcn/error.cc	Mon Jul 11 13:45:12 2016 -0400
+++ b/libinterp/corefcn/error.cc	Sun Jul 10 07:15:21 2016 -0400
@@ -36,6 +36,7 @@
 #include "defun.h"
 #include "error.h"
 #include "input.h"
+#include "octave.h"
 #include "pager.h"
 #include "ovl.h"
 #include "oct-map.h"
@@ -313,7 +314,8 @@
 maybe_enter_debugger (octave_execution_exception& e,
                       bool show_stack_trace = false)
 {
-  if ((interactive || forced_interactive)
+  if ((octave::application::interactive ()
+       || octave::application::forced_interactive ())
       && ((Vdebug_on_error && bp_table::debug_on_err (last_error_id ()))
           || (Vdebug_on_caught && bp_table::debug_on_caught (last_error_id ())))
       && octave_call_stack::caller_user_code ())
@@ -720,7 +722,8 @@
           && ! discard_warning_messages)
         pr_where (std::cerr, "warning");
 
-      if ((interactive || forced_interactive)
+      if ((octave::application::interactive ()
+           || octave::application::forced_interactive ())
           && Vdebug_on_warning && in_user_code && bp_table::debug_on_warn (id))
         {
           octave::unwind_protect frame;