[rdiff-backup-users] Bump major release version for rdiff-backup?

[Otto Kekäläinen]

Hello!

With the adoption of librsync2 the old MD4 hash is no longer supported
and thus a non-backwards compatible change is introduced. All backups
must therefore start from "scratch".
See https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=776246

Also, the Python 3 rewrite is a major thing. Therefore I suggest the
next release of rdiff-backup would bump the major version number and
become 2.0.0 (or even 3.0.0 to tribute Python 3).

What do you think?

- Otto