A couple of small fixes during the grace period.

• I had to cut ending music from v1.0 after discovering an issue with it. The issue has been fixed and so the ending music has now been restored.
• There was a bug where an unexpected noise would sometimes play when clicking on buttons at the start of the game. This is a web build specfic issue and has something to do with focussing. I've yet to identify the root cause but I've implemented a workaround whereby there's a short pause after clicking the begin button.