move new interpreter class to separate file * libinterp/corefcn/interpreter.cc, libinterp/corefcn/interpreter.h: New files. Move interpreter class and some supporting functions here from octave.h, octave.cc, toplev.h, and toplev.cc. Move main_loop into the interpreter class. Handle exiting with a separate exception object from interrupts, passing the exit status with the object. Update other files as needed to remove toplev.h or include interpreter.h instead of toplev.h. * libinterp/corefcn/module.mk: Update. * toplev.h: Deprecate.