Updated comments; removed unneeded includes
Removed debugging
Turned on wrapping for descriptive settings labels
Removed commented-out debugging
Revamped quality(effort) function

quality(l) is now ((l+1)^{1-alpha} - 1) / (1 - alpha), which has some
nice properties: q(0) = 0, q(l) >= 0, and q(l) = ln(l) when alpha = 1.

This lets quality equations not have to bother with the sign-preserving
crap (the next commit will remove that), because q values are now
always (weakly) positive.
Reformulate demand belief (now has P,q,P^2,q^2)

The demand belief previously had P^D and q^D terms (though not quite:
the exponentiation on q was sign-preserving because q could be
negative, which is no longer possible).

The two terms have now become 4: P, P^2, q, q^2 (in the 2d case, this
means adding linear terms, in the 1-d case, this is adding squares, and
in other cases, the models are non-nested).
Stop passing primitive types by const ref
Profit model change: now quadratic in quality

Previously the profit model had just a q^D term (where "^" preserved
sign for negative q values); now the model has q and q^2 terms instead
(and the sign-preserving bit on the ^2 is dropped, since q values are
now non-negative).
Added missing model restrictions

These were mentioned in the documentation, but not actually present.
Incorporate Demand/Profit model changes