bugfix for msmbuilder issue #247 regarding loading prepared trajectories. If the metric is RMSD or a hybrid metric, then just the trajectories are loaded. But I needed to add a check for LPRMSD, buuuut this doesn't work since it's a plugin. So, the change is to only load prepared trajectories if the metric is in an instance of a subclass of Vectorized. This should work because then we can use np.concatenate on the prepared trajectories. All other metrics are handled by loading trajectories and preparing later.
messed up in the bug fix. Needed to have metrics.Vectorized
added fix for Cluster.py to work with hierarchical. I broke it earlier...
Merge pull request #248 from schwancr/lprmsd_cluster_check

bugfix for msmbuilder issue #247 regarding loading prepared trajectories...