Fix 83, fix 123, minor other stuff

* Fixes #123
* Fixes #83
* Renames ayop-navigation.js variable "timer" to "playforward" as suggested by the "TODO" in the file

We could also throw #124 into this pull request (which is why I made a separate branch) if we can agree on the new label before this is merged.

Diffs are best viewed in [ignore whitespace mode](https://github.com/deplicator/xkcdTime_atyourownpace/pull/125?w=1) (`?w=1`), because I did a bit of reformatting/reindenting.