Monitor and alert system for time spent in game.

Technical Notes:

Alert intervals use "game minutes" and will be affected by anything that
changes game speed. Any mods or commands that changes the game speed and/or
game performance preventing the game running at 60ticks/s will produce
incorrect "in real-life" timings.

If you need precise real-world timing you'll have to resort to methods that
don't depend on the game engine. E.g. setting up an alarm in real life.

For more details check: https://wiki.factorio.com/Time

Due to technical limitations of the modding API, it is not trivial to
determine the session length of the player hosting a multiplayer server
or playing in single player mode.

Players in such categories should reset the timer manually by issuing:
/wellbeing reset-timer
at the start of each session.

For the remaining players the timer is reset automatically when the
player joins the game.

Release Notes:

0.0.1
- Add configurable setting to specify the alert time interval. Setting this to 0 disables the alerts.
- Add /wellbeing reset-timer command. This resets the player's running session time.