rtrek 0.2.0 release

• Added an initial version of an API function memory_alpha along with a collection of internal support functions for accessing Star Trek data from web portals available on the Memory Alpha website.
  • Internal portal functions that return data from portal and portal category web pages, and which may run recursively when necessary to compile complete content over multiple pages, are memoized.
  • Functions like ma_article, which return article content from a terminal endpoint are not memoized.
• Added ma_search function for using the Memory Alpha site search via URL parameters.
• Added ma_image function for downloading source images from Memory Alpha and loading into R as ggplot objects.
• Added an initial version of an API function memory_beta and other mb_* Memory Beta analogs to Memory Alpha website functions.
• Added mb_timeline for working with data from the Memory Beta Chronology.
• Added new datasets, mainly to timelines: tlBooks, tlEvents, tlFootnotes. Also added stSeries names and abbreviations table.
• Renamed st_book_series and stBooksWP to st_books_wiki and stBooksWiki, respectively.
• Updated tile set URLs.
• Updated stBooks dataset. This data frame now has better formatting, greater consistency, duplicates removed, and contains more entries than before. It is still incomplete and imperfect, but much improved over the previous version.
• Updated stBooksWiki dataset. Updated column names for consistency.
• Updates the acronyms used in the package for consistency.
• Update unit tests, added unit tests for Memory Alpha and Memory Beta functions.
• Updated function documentation.
• Updated introduction vignette sections. Added new section relating to timeline datasets.
• Added three new vignettes for each of the three API options: STAPI, Memory Alpha, and Memory Beta.
• Minor bug fixes.