* defs.h, main.c (catch_errors): Add return_mask arg.

	* defs.h, main.c (catch_errors): Add return_mask arg.
	stack.c (print_frame_info): Pass RETURN_MASK_ERROR.
	other callers: Pass RETURN_MASK_ALL.
	(return_to_top_level), callers: Add return_reason arg.
	* utils.c (quit):
	Use return_to_top_level (RETURN_QUIT) instead of error ().
	* main.c (main), tm-nindy960.h (ADDITIONAL_OPTION_HANDLER):
	Use SET_TOP_LEVEL not setjmp (to_top_level).
	* remote-nindy.c: Use catch_errors not setjmp (to_top_level).