Prevent zero datapoints being selected in the range slider.
Prevent zero datapoints being selected in the range slider.

from glasnt/rickshaw:limited_slider, extended for array-based RangeSlider objects.

glasnt/machiavelli,machiavellian/machiavelli,glasnt/machiavelli,machiavellian/machiavelli,glasnt/machiavelli,machiavellian/machiavelli,glasnt/machiavelli,machiavellian/machiavelli