Word ordering for wmTimer API wasn't consistent.
- Use "WM_event_timer_" / "WM_event_timers_" prefix.
- Rename "wm_window_timer" to "wm_window_timers_process"
because it wasn't clear what the function did from its name.
- Rename "wm_window_process_events" to "wm_window_events_process"
for consistency with "wm_window_timers_process".