Log Message:
Update to 2.2.4.2:

2.2.4.2 (stable):

* Namespace sigc is now documented, in order to make large chunks of the
  reference reappear.  (Daniel Elstner)
* The shipped reference documentation has been regenerated using Doxygen
  1.6.1, so that the document type is now XHTML 1.0.  (Daniel Elstner)
* The shipped Devhelp file has been generated with a newer version of the
  XSLT script in mm-common, so that documentation groups no longer appear
  as namespace prefixes in the keyword list.  (Daniel Elstner)

2.2.4.1 (stable):

* Reenable the per-class hierarchy graphs in the reference documentation.
  (Daniel Elstner)
* Drop the custom HTML header and footer, and use the shared doxygen.css
  file from mm-common. (Daniel Elstner)

2.2.4 (stable):

* New build system based on mm-common. The mm-common module is now
  required for building from the git repository, but not for builds
  of release archives. (Daniel Elstner)
* The public reference documentation is now hosted on library.gnome.org.
  (Frédéric Péters, Daniel Elstner)