Evoluton to move to 12 month releases

[Matthew Barnes <mbarnes redhat com>]

I wanted to let the release team know that the Evolution team has
decided to move from a 6 to 12 month release schedule.  This will
begin with the Spring 2014 GNOME release.

The rationale for this is rooted in the fact that because the code base
of the Evolution suite (including E-D-S and the Exchange extensions) is
so large and our development team is so small, we can only realistically
support one stable release branch at a time; currently that's gnome-3-8.

We have found that not only would the development team like a longer
development window for landing and testing large changes, but moreover
the current practice of abandoning a supported branch every six months
leaves our users in a perpetual game of catch-up, since even distros on
a semi-annual schedule generally release several months after the GNOME
release.  The current situation is frustrating for everyone.

The details of our plan is as follows:

- Release 3.10 this fall and 3.12 next spring in sync with GNOME.

- After the 3.12 release, move to an annual instead of semi-annual
  release schedule.  We will sync up with GNOME's spring releases --
  including the string change announcement and freeze periods leading
  up to the spring release -- and skip GNOME's fall release entirely.

- Throughout the rest of the year we will make monthly releases of
  our stable and development branches on a more predictable schedule
  (1st Monday stable / 3rd Monday development, or something like that).

- We'll continue with our current even/odd versioning scheme, which
  means Evolution versions will gradually fall behind GNOME.  While
  this may cause some confusion in the short-term, it leaves open
  the option of resyncing with GNOME's semi-annual schedule and
  version number at some point in the future.

This was discussed and approved within the Evolution team at GUADEC,
and we've had a supportive response on our user mailing list.

I'd appreciate any feedback from the release team.

Matthew Barnes