Add timestamps to position and behavior events (#147)

* Add timestamps to position events and behaviors.

- Take original event timestamps into consideration so nested tap-holds have proper timing.
- Add position and timestamp to keycode state changed event so the one-shot behavior can properly identify other keypresses and timings.
- Add timestamp to position events received from peripheral

* reduce number of arguments to behaviors

app/include/zmk/events/position-state-changed.h

@@ -13,6 +13,7 @@ struct position_state_changed {
     struct zmk_event_header header;
     u32_t position;
     bool state;
+    s64_t timestamp;
 };
 
 ZMK_EVENT_DECLARE(position_state_changed);