v 0.2.1

• The aspatial_siri function now kills off populations at or below the abundance threshold (previously it killed off populations below the abundance threshold only)
• The disease_dispersal function can now handle the case when one or more segments of the population does not disperse.
• Important bug fix: the number of occupied indices now updates more frequently within the
  disease_simulator function, which allows species range to expand properly.
• Documentation update: all references to features in development that are not yet
  implemented have been removed.

Full Changelog: v0.1.1...v0.2.1