Add an optional field 'lastDir', storing each hero's last order

Hi. So, due to heroes being teleported upon their deaths (which can trigger more deaths and more teleportation) it can be hard for an AI to determine exactly how the opponents moved. Since this data is readily available to the server, I request to add it to the player input in the form of "lastDir" field that records hero's last order (as one of the "North", "East", "South", "West" and "Stay" strings).

I've tested the patch locally, and it seems to produce the correct data in both player input and the events stream.