Initialization via Sequential Prediction

[ryanneph]

Instead of random initialization used currently, use "Sequential Prediction" as described in Sec 5.1 of https://cs.stanford.edu/~pliang/papers/permutation-dp-icml2007.pdf:

sequential prediction: a clustering is sampled according to the CRP but weighting the probability of choosing a cluster by the predictive likelihood of the new point given the existing points in the cluster.

which can be seen as a sort of 0th iteration with incrementally growing class/group membership as each data point is introduced to the sampler. wang notes that "this works well empirically"