Use base model 'data' implementation for non Variable items.
Added Hierarchical Clustering widget.
Added hierarchical clustering icon.
Removed unused code.
Merge branch 'master' into hierarchical-clustering
Changed input/output type declarations to DistMatrix.
Moved hierarchical clustering functions...

... under Orange.clustering.hierarchical namespace.
Added basic unittests for hierarchical clustering.
Added MDS widget.
Added MDS widget icon.
Merge pull request #152 from janezd/classification-tree-graph

Classification tree graph
Added GUI controls for cluster selection.
Remove unused code.
Merge branch 'hierarchical-clustering'
Added Torgerson (PCA) initialization.
Fixed an index error when no data is present.
GUI fix.
Merge branch 'mds-widget'
Word wrap the data table widget's info text.
Decreased too large random upper bound for jittering (32-bit windows).