Make players a defaultdict

The players dict is a defaultdict with missing keys being a defaultdict
with missing keys being ints. This should make it easy to add new
players and increment their stats without pre-enumerating things.
Start allotting stats

Just the basics are being done. Need to work on many more events.
Add stat for generic outs
Handle stolen bases and caught stealings

"Handle" that is. This is complicated.