Allows dependencies to be economically expressed and used.
For example, see the new definition of subtract.
Credit for the basic idea goes to James Drew, see
https://stackoverflow.com/a/41525264Resolves#21.
Also starts each PocomathInstance with no types at all, and uses the new
situation to eliminate the need for a Complex "base case".
Resolves#14.
Resolves#13.
Co-authored-by: Glen Whitney <glen@studioinfinity.org>
Reviewed-on: #15
