Add how-to on creating a generator from scratch

[7sharp9]

[travis-leith]

I have an idea for a case study that would make a good how-to.

A generator that, given a DU type 'a with individual cases of types 'b, 'c, 'd, ..., can generate a function with the signature a' seq -> 'b list * 'c list * 'd list * ...

The function takes a DU type sequence and splits it into separate lists for each case.

[7sharp9]

tuplising things or listifying things was a plugin that aI would like to do. Such as:

[Myriad.tuple]
myType = ...
let test = myType.create ...

let tupled = MyType.toTuple test
let result = MyType.fromTuple tupled