[3896] Nowy ekran - timeline.

https://gist.github.com/lukkolstx/4693138a2ace6d819ac4
Well. If we already have something like `parseInterval()` we should make use of it. Sending timestamps (pure integers) is quite clean, lite, and ready to use everywhere. 
Re-factoring is always tempting but let's say this is not the time for this.