Add support for using a range slider to set criteria values

[bicarbon8]

The Range Slider would constitute a new type of Criteria where the user must specify a numerical worst and best value that form the range of allowed selections and optionally a step value (defaulting to 1). When selected, the user would use a slider to choose the value and each step would be determined by the step value used when the criteria was defined.
if the criteria conditions are edited after setting values for list entries, the editing of an entry should display a validation error if the value selected is no longer in the allowed range, but otherwise it should not show any validation error.