Minor fixes to clustering of clustering test

Made a minor fix to the clusterer distance computation method. Before it
cached the cluster of each object for each clustering but then didn't
use it. It does now. Also, now prints out a table of the distances
between clusterings for each context.
Added ScoredChangeExpWeightedClustering

Added an experimental setup that performs weighted combination of the
contexts. It uses the clustering method of solving the tasks from before
but also does 5-fold cross-validation across the 50 MRT's to train a
weight for each context (just attempts to solve the train tasks with
only that context, and then normalizes all the weights) and then
multiplies the output of the compare method for each context by the
weight, thereby dimenishing the influence of useless contexts.