Removed Scaled

We won't be scaling coefficients to all be within [-1, 1] -- we need the
highest order term to be a monic monomial of sorts and so we'll only use
monic.
Fixed asEquation to handle = 0 case

Fixed so that when we have something like y' = 0 we still get an
equation. Drop zeroes had gotten rid of it so we'd end up with y' =
which is nonsense.
Fixed term sorting

Terms sort in better order now.
to_hash understand non-linear ODEs now

The method for turning a parsed result into a hash now understands how
things should look now that things like 2y'y'' can be terms.