hmat: fix installation of hmat addon (headers are copied in includes/ScalFmm/HMat/Src/.../*.hpp or includes/ScalFmm/HMat/CClusteringLibrary/*.h); Still need to fix pb when including cluster.h.

HMat: Provided data files (single precision) for mds (biology) in order to test clustering; Provided test routine and class for k-means clustering (actually k-medoid, since more robust and uses only distance matrix); Connected components can now be performed on a distance matrix read from file.