[Get.pm] Return DOIs with book records from EBSCO.
[Get.pm] Support DOI search of books.
[Get.pm] Added ISBN search for EBSCO.
[Get.pm] Added ISBN search for the LoC.
[cite.pl] Added ISBN search.
[Get.pm] Don't crash when no search terms are provided.
[Get.pm] Removed a stray debugging line.