Fix appveyor build.

Don't exit main() on emscripten.

Split sound functions into backend and front-end.

Fix FreeBSD build.

Add another tune to play when player reaches the last live.

Define active music states symbolicly.

Define digger states symbolicly.

Make sure state of a player that has no lives don't leak over to the

Decouple sound generation from the main thread to not share state

Make title animation into a separate TU.

Add netsim mode.

Unify logs and make sure to lock it so it does not become garbled.

Don't define GetAsyncKeyState - it conflicts with SDL.

Add Windows build glue and GitHub Actions CI pipeline

Fix bugs in the simultaneous multiplayer mode: