Removed two fmt.Sprintf() calls and a fmt.Printf() call. The Printf()
was for debugging and isn't needed anymore. Sprintf() apparently
isn't all that performant.
Implement some commands in the wasm client code:
- /playing (setting and clearing)
- /refreshplayer
Commands not yet implemented:
- /purge (command doesn't exist yet on server)
- /help (doesn't open window)