CluStream.WithKmeans: How about changing the macro and micro clusters ids when getClusteringResult() is called, to show the labeling?

[onofricamila]

Hey! I was diving into the source code of
moa/moa/src/main/java/moa/clusterers/clustream/WithKmeans.java, and found out that it would be really useful if right after the user calls getClusteringResult(), the macro clusters returned have a unique id (current id is -1 for all of them), and then when the user calls getMicroClusteringResult(), these ones have a coherent id too, representing the former labeling (current micro clusters id is -1 for all of them) ...

It seems that the moa/moa/src/main/java/moa/cluster/Cluster.java setId() method is not used and I do not know if that is on purpose (like for some reason).

Having the micro clusters labeled would be useful for calculating metrics to see how well the clustering resulted, for plotting different groups with different colors, and so on.

If you think what I remarked is correct, I will submit a PR.

Any feedback is welcomed. Thanks!!