* unit tests for 'sannbox'

* Create objective functions for 'probe.match', 'traj.match', and
   'spect.match' so that  users can roll their own optimization
   routines.  Use 'nloptr' as the target optimizer package?

* Improve 'pmcmc' to take advantage of all particles.

* Partial rejection control for 'pfilter'?

* Better documentation/rationalization for 'zeronames'.

* It might be possible to make the writing of basic model functions
   using R expressions rather than functions.

* Write 'plot' method for 'pfilterd.pomp' objects.  This would display
  effective sample size, conditional log likelihood, filter means,
  prediction variances, prediction means?

* Add plugin for adaptive tau leaping algorithm.

* Parallel 'pfilter' algorithm.

* Add LPA model example.

* Extended Kalman filter.

* Plugin for compartmental models.

* Adaptive particle numbers in pfilter.
