P-class window settings

[DavidGarfinkle]

P1, P2, and P3 don't currently support filtering by pattern or source window size like S1, S2, W1, and W2 do. This is more or less because the algorithms themselves don't rely on a window whereas the design of the SW algorithms (specifically the pre-computation of their K-tables) use pattern and source windows.

I'm suggesting we include a result filter so the settings usage across all algorithms is consistent. We could modify the algorithms a bit to possibly increase runtime by including window settings, but I suspect this wouldn't have any noticeable effect on the current runtime, judging by the way they currently work.