refactoring

There are now two modules:

• bascpp features the core "barebone", generic methods.
• dypac has the object class for fMRI data

The method has also been changed: now stab_maps are extracted and trimmed within batches, and then matched and averaged across batches by a separate consensus clustering. Hopefully this approach will scale very well.

Important change in the API: n_states now controls the total number of states, which before it was the number of states per cluster.