[Finishes 66739368,67045676,67112678]: add launchBall block, randomize ball position/angle

in addition:
add dynamic creation of balls - retain ballImage, ballSpeed for new balls
retain originalBallCount so new balls are deleted while originals are reset during "Reset"
add ballFlags to prevent strange problems like bouncing balls that already went through the goal, re-launching a ball twice, etc.
added various logging for debugging (commented out)