Tab-separated output

This code changes the script to give a tab-separated output, which would be more useful to produce plots and do analysis.

I had to add a new entry, the ID of the player, to the tuple defining each player. This is to keep track of which player is which, since the order of the players is shuffled after each round. 

This changes modifies the output of the script, in a way that is not compatible with the previous implementations, so it's ok if you reject it. The optimal solution would be to add a command line option to specify whether the output must be in the previous format, or csv. However, I guess that you will prefer to decide how to implement it.