Modify to fit the needs of Openfest:
- lecture time of 45 min
- lightning talks time of 5 min
- multiple halls
- more control actions

Updated packages, fixed breaking changes
Added a seperate control page
Cleaned up unused code

This reverts commit e5a6270.

So code isn't so ugly

We don't need to depend on this...
Vanilla JS is good enough for getting an element by its id

1. Move away from CommonJS
2. Use the `class` syntax sugar for the stopwatch
3. Fix some math
4. Support more rooms

Timers should be configurable now
Also, the server won't hang when restarting, so we don't need to `kill
-9` it.

Use a monotonic clock to know how much time has actually passed
(Not all clocks are created equal...)