Make the Krausest benchmark code stream-oriented

[dariomannu]

The current Krausest benchmarks created in #42 look ok, but are too much object-oriented (as originally conceived by Stefan and the team). Rimmel is a stream-oriented library so we should showcase this paradigm instead of OOP.

• remove the store: only use pure streams instead
• only use derived streams: no calls to stream.next(). You get derived streams with the zip, withLatestFrom, combineLatest and similar RxJS operators.
• feed streams directly from buttons: no onclick="${() => doSomething } but onclick="${stream}". This article gives an idea how you turn plain functions into streams you can later compose.

If anything is unclear (which is normal, given SP is a new paradigm), don't hesitate to ask!

[dariomannu]

We'll want to use some Custom Sinks optimised for fast table/row rendering, so we can show how Rimmel can be customised for performance and/or memory-sensitive applications.