Took unnecessary extension of lambda_* datasets out of posterior.  Added stop() to summary method to prevent barfing if posterior is empty.

Replaced calls to uuid package with a queue-based labelling system in the Dirichlet Process.  Here, we create as many labels as there are data point, then pull labels out of the "pot" as we need, and replace them after use.  This allows us to remove the extra randomness in the DP process caused by the uuid generator (quite rightly) being independent of R's PRNG.

Added code to check source data does not have all 0's for a type for all times, and to check it was identical for each location (within a time).