Updated with ability to track total score average and score per shooting position, averaged across multiple shooting rounds. Also added "Undo" button to reverse a mistaken HIT vs. MISS, or MISS vs. HIT entry.

New features:
-- Average of total score over multiple rounds
-- Average score each shooting position over multiple rounds
-- Ability to select starting shooting position
-- Ability to Undo a mistaken HIT for a MISS, or MISS for a HIT