Formally specify Qi Normal Form

[countvajhula]

We've talked about Qi Normal Form a lot and have implemented a lot of normalization rules in the compiler, bu we haven't actually defined what Qi Normal Form is aside from saying that it's a "simple" and "reduced" canonical form of the source syntax. It will likely be informed by the specific optimizations we hope to do, since these optimizations may impose requirements on the normal form.

See also: Qi Normal Form and Proving Correctness