GUI: no more extra command queue for debug commands * main-window.cc (constructor): remove initializations for debug queue; (debug_continue,debug_step_into,debug_step_over,debug_step_out,debug_quit): queue new debug commands into common queue; (queue_debug): removed obsolete function; (execute_debug_callback): move this function into the execute method of the new octave_cmd_debug class; * main-window.h: remove obsolete prototypes and class variables * octave-cmd.cc (octave_cmd_debug::execute): execute method of new class for debug commands; (octave-cmd.h): changed private into protected for inheritance, new class octave_cmd_debug derived from octave_cmd_exec

--- a/libgui/src/main-window.h
+++ b/libgui/src/main-window.h
@@ -288,10 +288,6 @@
 
   void queue_command (octave_cmd *cmd);
 
-  void queue_debug (QString command);
-
-  void execute_debug_callback ();
-
   void configure_shortcuts ();
 
   workspace_model *_workspace_model;
@@ -404,11 +400,6 @@
   QSemaphore   _cmd_processing;
   QMutex       _cmd_queue_mutex;
 
-  // semaphore to synchronize debug signals and related callbacks
-  QStringList *_dbg_queue;
-  QSemaphore   _dbg_processing;
-  QMutex       _dbg_queue_mutex;
-
   bool _prevent_readline_conflicts;
   bool _suppress_dbg_location;
   bool _start_gui;