change default Kmeans init method to "Furthest"
rationale:
  // default Initialization is Furthest. Better results for hard cases, especially with just one trial
  // in the browser. PlusPlus can be biased, so Furthest can be best, again especially if just one trial
  // Random should never be better than Furthest.

Additionally, both the PlusPlus and Furthest inits should now be better than random, substantially. I've seen cases where the number of extra Lloyd iterations needed after the 5 iteration init, is 0. So init of random (None) would be lower performance in some number of cases. random should never give better results. I've seen some bias in PlusPlus for certain kinds of datasets. Furthest seems best