More illiquid asset solver improvements

Problem at the bottom of the state space was due to tiny (1e-16) violations of the lower boundary, easily fixed. Consumption function is still "wiggly" from the perspective of (m,n) space. Might need to implement vPPfunc and cubic spline interpolation, and *also* might need to conduct a more precise search for the bounds of the region of inaction, taking expectations repeatedly. Setting aside for now.