Log Message:
Update to 2.16.1.  Changes since 2.15.93

* Add guile-clutter to the set of configurable packages.
* Removed the "docs" module; its content, the tutorial, is now folded
  into the documentation for all of the relevant modules (e.g. GLib,
  GTK+, CORBA, etc.)
* Changelogs have all been archived to ChangeLog.pre-2.16, because now
  we will just use revision control logs.
* Formally require Guile 1.8, as has been the case for a while now.
* Bump the API_VERSION to 2, as a test before going stable.
* Support a variant of check-coverage that generates a texinfo file with
  the missing functions.
* Various buildfixes for building out-of-tree modules such as
  guile-gnome-gstreamer.
* Build system work: add common makefile include for unit tests and a
  new check-coverage target to documentation builds.
* Added infrastructure to make documentation.