Rework of Supervoxel classes
    Renamed OctreePointCloudSupervoxel class to OctreePointCloudAdjacency - now it is general, not just for supervoxels
    Renamed Supervoxels  to SupervoxelClustering. Now works better, allows for a transform etc..
    Also added a simple function in PCLVisualizer to check for existence of an id in the actor map