Add auto-blocking parameters to adaptive covariance methods

[ben18785]

Reference here. Think this approach or others like it (I haven't searched thoroughly) may considerably speed up sampling for many ODE models.

[MichaelClerx]

We propose an automated procedure to determine an efficient MCMC algorithm for a given model and computing platform. Our procedure dynamically determines blocks of parameters for joint
sampling that result in efficient sampling of the entire model.