Current release schedule

[Christian Stimming]

Also, we should have some policy about the freezing of the app behavior
so that the user docs can be (re)written, with some additional time
for the translations of the user doc to be written.

I.e. after the feature freeze every behavioural change has to be
announced to the documentators. After the string freeze every change
in strings has to be approved by at least two developers and has
to be announced to the translators -- as a proposal.

Christian