adaptors now return an ObservationSequence object
change XMLAdapterComplexA to include delay to previous event of same type as well (instead of 0)
add two additional event/delay-based XML adaptors for multivariate observations; revert change in previous commit regarding delay to previous event of the same type (this is now 0 again).
make XML adaptor names more comprehensible
add XML adaptors for window-based multivariate observations
update XML serialisers to deal with sklearn.hmm classes
update XML readers to deal with sklearn.hmm classes
add error handling for XML files with invalid subsession structure, i.e., a different number of <startSession> and <stopSession> markers.
adjust error handling for XML files with invalid subsession structure, i.e., a different number of <startSession> and <stopSession> markers.
implement prototype pipeline for completely unsupervised GMM HMM learning
init visualise package