Multiplexing Mixins

[pgulley]

Researchers often want queries run against a multiplication of two or three parameters- ie five queries with various settings for n-gram size or entity filters.
It would be cool to be able just list the values of the parameter types once, and calculate the permutations at runtime.

Right now we read from the YAML files directly in the templating step, but it could be abstracted out to allow this kind of thing.