Log Message:
update to 2.0.13
changes: many fixes and improvements

reviewed by John R. Shannon

pkgsrc notes:
-since S/MIME support is the biggest difference in functionality over
 gnupg1, enable it per default -- my tests (with the s/mime plugin
 of claws-mail) worked
-left the build against a private libassuan with GNU-pth support
 alone for now, just updated libassuan to 1.0.5. We might build
 pkgsrc/libassuan against pkgsrc/pth at some point, but this needs
 to be checked for side effects. (As this pkg doesn't export a library
 which might propagate the pth dependency, the possibility of
 pthread-pth conflicts should be limited. Other uses of libassuan
 need to be checked.)