[Get.pm] It's now "PLOS", not "PLoS".
Updated the copyright year.

I changed the starting year to 2011 because that's when the first commit is dated. I don't know why I initially put just 2012.
[Get.pm] Silenced a warning.
[quickbib.py] Replaced the option "also_return_keys" with "return_cites_and_keys".
[Get.pm] A regex tweak for a server-side change.