move hmm code from pyprobml to JSL

[murphyk]

move these to jsl/hmm

hmm_sgd_lib.py
hmm_utils.py
hmm_discrete_lib.py
hmm_discrete_lib_test.py
hmm_discrete_em_lib.py
hmm_lib_log.py
hmm_lib_log_test.py
hmm_discrete_likelihood_test.py

move these to jsl/demos

hmm_casino_demo.py
hmm_casino_em_train.py
hmm_casino_sgd_train.py
hmm_lillypad_demo.py
hmm_self_loop_dist.py
noisy_spelling_hmm.py
visual_spelling_hmm_daft.py