Add elapsed/duration timer for slider.
Rename Choreographer to ChoreographerWorker.
Split Choreographer.

Separate Choreographer and Choreographer give us
flexibility to control robots by dance timeLine from not omly
from dance cycle.
Makes scenario loading more flexible.

Move loading danceScripts from isDanceReady to loadScenarioFromFile.
Apply FileLoadError to DanceScript loading.
Make scenario reload on on user change config.

Each time user chooses another dance or reassigns files to robots,
scenario will reload and total dance time will be recounted and
displayed on form.
Add updating current/max label for index.
Fix selecting "None" scenario line.
Robots control by slider.

If scenario loaded correctly and robots are connected and DC is
connected for them, user is able to set certain frame of dance on
robots by moving slider.
This is unavailable during dance and slider is reset on dance
start/stop.
Fix slider control in release.

In release moving slider with not connected robots not showing
errorMessages.
Bump to version 1.6.0 before field tests.