2022.03.16 -- Version 2.5.6

Antonio Quartulli (4):
      GitHub Actions: update script to same version as master
      update copyright year to 2022
      keyingmaterialexporter.c: include strings.h
      remove unused sitnl.h file

David Sommerseth (2):
      sample-plugin: New plugin for testing multiple auth plugins
      plug-ins: Disallow multiple deferred authentication plug-ins

Frank Lichtenheld (2):
      doc/Makefile: rebuild rst docs if input files change
      doc/options: clean up documentation for --proto and related options

Gert Doering (4):
      fix Changes.rst errors in 2.5.3 and 2.5.5 announcement
      Repair --inactive with 'bytes' argument larger 2Gbytes.
      Fix --mtu-disc maybe|yes on Linux.
      Preparing release 2.5.6

Ilya Shipitsin (1):
      CI: github actions: keep "pdb" in artifacts

Lev Stipakov (7):
      auth_token.c: add NULL initialization
      vcpkg-ports/pkcs11-helper: bump to release 1.28
      vcpkg-ports/pkcs11-helper: indicate OpenSSL EC support
      msvc: cleanup
      vcpkg: link lzo statically
      vcpkg-ports/pkcs11-helper: adapt to new upstream URL
      vcpkg-ports: add openssl 1.1.1n