v0.28.0
- first version with change from libssh 0.7.x -> 0.8.x
- update to libssh 0.8.6 from https://www.libssh.org/files/0.8/libssh-0.8.6.tar.xz (changelog see https://www.libssh.org/2018/12/24/libssh-0-8-6-xmas-edition/ and for previous versions https://git.libssh.org/projects/libssh.git/tree/ChangeLog?h=stable-0.8)
- small adaptations to corresponding api changes