When the ball hits the side of the paddle, it would get stuck because
the paddle moves faster than the ball. This commit forces the post-
collision vertical velocity of the ball to be going up and makes sure
that new ball's y-position is higher than in the previous frame.
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
