Improve countdown sound logic
Improve countdown sound logic

Calculate the best countdown sound on the fly
rather than relying on a prompt timeout callback.

Fixes sound weirdness in chrome when tab is not in foreground.
Tested extensively on Chrome, but should be safe for all browsers.

clarkerubber/lila,luanlv/lila,luanlv/lila,luanlv/lila,luanlv/lila,luanlv/lila,clarkerubber/lila,luanlv/lila,clarkerubber/lila,arex1337/lila,clarkerubber/lila,arex1337/lila,arex1337/lila,clarkerubber/lila,arex1337/lila,clarkerubber/lila,luanlv/lila,arex1337/lila,arex1337/lila,arex1337/lila,clarkerubber/lila