(swallow_events): New arg DO_DISPLAY.

(swallow_events): New arg DO_DISPLAY.

(swallow_events): Process timer_event events here.
(detect_input_pending_run_timers): New function.

(Vtimer_idle_list): New variable.
(syms_of_keyboard): Set up Lisp var.
(timer_check): Check for idle-time timers too.
Expect timers to have 8 slots.  Initialize triggertime.
(timer_start_idle, timer_stop_idle): New functions.

(get_input_pending): New arg do_timers_now.
(readable_events): Likewise.
(Finput_pending_p): Use get_input_pending, so we can specify
1 for do_timers_now.

(timer_check): Check for difference being zero.