copre 0.1.0

Initial release.

copre 0.2.0

Replaced mdp() and polya() with gibbsmix() and seqre().
Created a base plot method and loosened dependency on ggplot2.
Minor bug fixes.
Added a NEWS.md file to track changes to the package.

copre 0.2.1

Fixed a Debian compile warning.
Typo corrections in documentation.