Hi Guix,

the attached patch set adds a new “animation.scm” module containing
Synfig Studio, a really nice 2D animation suite.

A couple of patches and substitutions were needed to make Synfig build
with our version of libsigc++ and the latest version of libxml++ (added
with the first patch).

I added ETL to the “animation.scm” module, even though it isn’t much to
do with animation.  It is, however, part of the Synfig sourceforge
project, its release tarball is to be downloaded from under the
versioned Synfig URL hierarchy (so its URL must be synchronised with the
Synfig version), and it doesn’t have its own project page.

~~ Ricardo