jstor 0.3.3

Removed functionality

• The option to download the most recent data on journals directly from JSTOR
  (as in jst_get_journal_overview(most_recent = T))
  had to be removed due changes on their server. I will try to find a solution
  with JSTOR support so we can add the functionality again.

New features

• jst_define_import now prints the specification in a pretty and informative
  way.
• jst_define_import now checks the definition more extensively:
  jst_define_import(article = jst_get_book) or similar mis-specifications
  will raise an error.
• Import the crayon package for more colourful error messages in some places,
  which are easier to read.

Bug fixes

• Removed an outdated function from the vignette on batch importing files.

Other changes

• The old group of find_* functions is now defunct (they raise an error).
• Updated cached version of journal data.