add a slidebar to /RadiaModel to set threshold

[esaule]

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[esaule]

/RadialModel takes a threshold parameter as a url parameter.
It would be good to be ableto control that threshold with a slidebar of some sort.
This may casue the need to add an intermedia component that would control the RadialModel component in some way.
Note that not all values of threshold are interesting only the one under the form of "x/courseIds.length"
So if the bar could be "sticky" to these particular points, that could be good.