gpg,gpgsm: Fix corruption of old style keyring.gpg files. This
bug was introduced with version 2.1.20. Note that the default
pubring.kbx format was not affected.
gpg,dirmngr: Removed the skeleton config file support. The
system's standard methods for providing default configuration
files should be used instead.
w32: The Windows installer now allows installion of GnuPG without
Administrator permissions.
gpg: Fixed import filter property match bug.
scd: Removed Linux support for Cardman 4040 PCMCIA reader.
scd: Fixed some corner case bugs in resume/suspend handling.
Noteworthy changes in version 2.1.21 (2017-05-15)