Testing float vs double precision in posterior
Fix missing changes from float_2d to double_2d
Updated Posterior/Forward/Backward to use Traceback table from Viterbi
in order to handle Explicit duration states

Also updated documentation in hmm.h, StochHMMlib.h

Commented out Graphviz printing
Add additional code documentation
Fix concatenation of sequence when calling getFasta sequentially.

When getFasta was called multiple times on a sequence it would concatenate the sequence instead of removing the previous sequence.

Added a check to import functions, if sequences is already defined.  It will now delete and reset the sequence to initial state