Naming version as upcoming one with "-pre" suffix.
This is how semver marks pre-release versions.
@mkroehnert It is probably good idea to always have "-pre"
and do the release process script with that in mind
(just remove "-pre", publish, increment and add "-pre").
IIRC this is how node does it; other projects probably, too.
@NicolasPetton Maybe there are more places where version is denoted, there it also should be changed.