Fix lumping

There were two bugs
1. In PCCA, the `n_states_` attribute wasn't saved on the class, and needed to be
2. In PCCA+, the number of desired macrostates in most of the code is communicated by the right_eigenvectors matrix, which is suppoed to be `n_microstates x n_macrostates`, but our code was just passing through all of the right_eigenvectors.