[Evolution-hackers] Last minute "vfolder-prep" branch merge

[Matthew Barnes <mbarnes redhat com>]

Srini asked me to merge his "vfolder-prep" branch in time for Evolution
3.4, and I wasn't around much last week so this is kind of last minute.

This branch just stages some of the vfolder and filtering code to be
moved to Evolution-Data-Server after 3.4.  The GTK+ parts of some of
those classes have been split into separate "ui" subclasses, similar
to how EMailUISession was forked from EMailSession.

The branch also introduces yet another little utility library named
libevolution-utils.  This is just a temporary library.  The plan is
to move its APIs into libedataserver[ui], but it's a little late to
do that for 3.4.  The library contains most of the EAlert APIs and
some other odds and ends from libeutil, so that created a bit of a
splash across the source code.

I know it's bad juju to do this right before a release, but the source
code is only being reorganized, Srini assures me it works well, my own
testing seems to confirm that, and I'm doing my due diligence to make
sure everything builds smoothly for Monday's release.

Matthew Barnes