A simple implementation of the glicko 2 algorithm.
I understand it is more than a year since the last update, but with all the five star comments I can not understand what happened at that update. In the current state, this does not work as intended: * According to instructions, the function call is $Object->Update(), where in reality it needs to be $Object->Update(NULL) or some other argument. * $M is often used instead of $this->M, causing the class not to function at all. * $M is at places misspelled $m * $this-> is missing in several other places. * $deltasq is misspelled $deltadg at one point. These are the ones I found now, but it is clear it has not been tested.