add option to query variations matching some range of image_consistency

[dmarx]

with image_consistency added to filename of variations and ability to "resume" with arbitrary variation settings, we can make scenes where images have a range of variances. ...oh hey, maybe it could be fun to specify a variations as a range, or a distributional RV like specifying alpha and beta of a beta distribution. users would probably be overwhelmed, so maybe I could parmeterize it that way under the hood, but then expose it to users differently... or even just parameterize it as mean and variance of the probability and then clean it up under the hood.