commit prior to messing with Omega likelihood (putting in N piece).

Fixed:
-Error in Dt.old: wasn't correct to store for future iterations because predicted omega, etc. change from iteration to iteration
-Error in gradient for L-H.  Tau.eps needed to be species specific
-Changed effective sample size for tau_eta updates to reflect rank deficiency of 2 for each knot
-Implemented RW2 for simulation so simulated and estimated can be matched up for debugging; note mean, slope of alpha = 0 when generated this way
-Now setting RW2 intercept, slope to 0.0 during estimation; getting "strange" results otherwise.