rcrossref v0.9.0

NEW FEATURES

• big Crossref Addin update (#171) all work by @haozhu233
• Async HTTP introduced for cr_works(), cr_works_(), and cr_citation_count(). See the new parameter async (logical) in those functions. For cr_citation_count(), it now accepts more than 1 DOI, and the output has changed from a numeric value to a data.frame (columns: doi and count). With async=TRUE for cr_works() you get a list of data.frame's; while for cr_works_() you get a list of JSON's (#121) (#160) (#182)

MINOR IMPROVEMENTS

• package tests now using vcr for HTTP request/response caching (#178) (#179)
• in works data, now returning published-print and published-online fields (#181)
• add new filters for /works routes (when works = TRUE): isbn, reference_visibility, has_content_domain, and has_domain_restriction (#176) (#177)
• add new return element in /works routes (when works = TRUE): $reference gives the references cited in the article (these are not the articles citing the target article, sorry) (#176)
• improve documentation on the "polite pool". If you supply an email address Crossref will put you in the polite pool (#173) (#175) thanks @poldham
• added example to cr_abstract() of handling many DOIs while allowing for failures without stopping progress (#174) thanks @zackbatist

BUG FIXES

• fix internal parsing of funder data in cr_works() (#180) thanks @nicholasmfraser for the bug report
• fix for cr_citation_count(): when given a bad/invalid/malformed DOI, throw warning and give back an NA (#164) thanks for the report @chreman
• Fix for instances in the package where we incorrectly were doing logical comparison's; detected via R_CHECK_LENGTH_1_LOGIC2