Memorials: Track # of steps taken

This PR contains: 

* The start of a stat tracking system - currently only tracks steps taken.
* More tracking can be added by:
  * Adding another field to the stats struct
  * Saving/loading the field in player.cpp
  * Incrementing/changing the field, whenever appropriate
  * Writing it out to the memorial file in memorial()
* Also includes an important fix to the fact that memorial logs were not loading properly (by which I mean "not loading at all").

I'll add more tracked stats in due time - but feel free to comment and offer suggestions.