added computed defaults for yaml_tag and PROPERTY_NAME
added computation of defaults for yaml_tag and PROPERTY_NAME to base class Feature
added describe_template_sets() for a dynamically computed description of the available sample template sets
updated docstrings
added Template.expand() and Feature.expand(), facilitating mass generation of Templates. Updated docs
template statistics now can be computed (and sorted) on provided test data, making an interesting comparison with the training
added a bit more training statistics to the trainers
quoted strings in verbose stringification of Template
updated batch_tag_incremental() to return the same statistics for testing as the tagger keeps for training
added functionality (learning curve and template stats) to demo(); many parameters now, but can be helped by providing some wrappers