gnumonik

Added a function for universal instantiation over constrained rows…

7

…, along with a supporting data type (Constrained) and type class (Known) to Data.Row.Records. This is an awkward place for it, but it doesn't seem like there's anywhere else where...

As Andrea pointed out to me, our typeclass system appears to be sound, but is only sound given a boatload of assumptions. I should write those down somewhere in order...