exp cmd widget: fix missing promt after error * octave-qobject.cc (base_qobject::terminal_widget): connect signals of interpreter events to terminal signals instead of slots * qt-interpreter-events.cc (display_exception): emit signal for new command line after exception message in eyp. terminal widget * qt-interpreter-events.h: new signal new_command_line_signal * terminal-dock-widget.cc (terminal_dock_widget): connect new interpreter triggered signal to related slot in console; (interpreter_output): removed, slot was only emitting a signal, which is now directly connected to the first signal; (update_prompt): dito * terminal-dock-widget.h: new signal new_command_line_signal, removed interpreter_output and update_prompt