v0.4.0

This is version 0.4.0 of the imag core distribution.

This is still experimental and alpha-quality, so expect bugs and so on.
For a more throughout release summary, please refer to the imag-pim.org
website of the project.

I know I always write down that this is alpha quality, but right now I
feel confident enough to tell you all: Test it out! Some things seem to
work rather smoothly by now, the store format is stable and I fixed a
hell lot of bugs in this release.

Also, the release is smaller than the releases before. That's because I
want to do smaller and faster releases instead of big ones where a lot
of things change.

So far, this seems to work nicely.