add preclustering step with stripped-down hmm

add an hmm step after hamming clustering which uses no v or d fuzz
and only one gene version per query sequence.

boo yah. works great. stripped hmm is faster roughly by a factor <v_fuzz> * <d_fuzz> *
<n_max_per_region>, e.g. at the moment 5 * 10 * 5 = 250