Rphenoscape release v0.3.0

This is a major new release with a renamed, restructured, and better streamlined API.

Note that this release is not backwards compatible with previous ones. Many function calls from the v0.2.x series remain available with deprecation warnings, and are slated for removal in 0.4.x.

Major changes include the following:

• a02c294 State symbol to label translation is now polymorphic state-capable
• 37d6354 Upgrades to using KB API v2, including
  • f1c6464 Replaces taxa corpus with annotated-taxa/taxon-variation (#254)
  • 41db43d Adds corpus=states to corpus_size/term_freqs
  • 8f58e1b Switches to named corpus kb phenoscape api
• Overhauls term category determination and use, including
  • 4083c01 Allows "entity" or "phenotype" for term_freqs() as
  • 58936f2 Removes subclass recursion and other fixes for term category
  • 629c814 Improves algorithm and documentation for term category
  • e01258f Removes term_freqs taxon_annotations corpus
  • 1a0390c Removes term IRI decoding logic
• 7589303 Adds mutual excusivity functions
• fc03aba Adds Owl class for use with get_ontotrace_data()
• 47f6c71 Adds terminfo class
• Streamlined and restructured function API and naming, including
  • 3759ab3 Combines NeXML char matrix functions
  • 527c3c5 Renames pk_get_IRI.R to get_IRI.R
  • 97a84bf Removes pk_ prefix from term.R functions
  • 4e353e0 Removes pk prefix from pk_is_descendant/pk_is_ancestor
  • 6dd42e4 Renames pk_get_study_xml to get_study_data
  • d38f801 Renames pk_get_ontotrace_xml to get_ontotrace_data
  • e7f5106 Replaces pk_*_class with term_classification
  • 52b6fca Renames pk_get_study_list to get_studies (#126)
  • 81eb0b9 Renames pk_get_iri to get_term_iri (#125)
• b535e62 Moved CI testing from GitHub action to CircleCI
• Various improvements to documentation and examples