Add outs in Linescore model

[faskowbn]

I'm working on a fun side project, and having the number of outs in each Linescore would help me with some business logic -- specifically, whether the game is done. Without knowing the number of outs in the last (and current) inning, it's challenging to know whether the inning is ongoing or completed.

The api has a somewhat odd structure in that outs are not associated with each inning; it is only on the outer layer. So in the code, we assume that every inning before the current one has had 3 outs. Knowing baseball well, I think this is a reasonable invariant!

I ensured that outs is being propagated as expected using the sample program for a current inning.

I also ensured that outs is being propagated as expected using an inning before the current inning.

[markjamesm]

Looks good to me. Thanks for your PR!