Histogram filtering is buggy

[Makosak]

When updating histogram filters on the right hand side, they stop at what seems like arbitrary breaks, and it's not clear what # they've stopped on. We'll need to refine this a bit more:

• Add more breaks/places for the filter to be stopped in the histogram
• Specify what number is being filtered somewhere within the histogram UI (so the user knows what threshold is being used)

Potentially, the number being selected for the filter can be shown underneath the histogram, on the left hand side. Later on we could add an indicator if this number is "low" "med" high" within the same line, on the right hand side.

[mradamcox]

Just clicking around a bit with it, seems to be snapping to divisions of tenths, which doesn't correspond to what's shown visually.