try to put some guards against unsafe state of sending events in the background; update links to the documentation; show current user location when coming from background; save channel name to constants; do not show last 24 hours of events when recording and coming from the background; refactor: hide private stuf of location manager, rename some constants
delay sending events when the application wakes up; add networking error details in the log; assert a stricter rule when sending the events: only when application state is UIApplicationStateActive