Log Message:
Update to 2.2.8, to fix compilation with gcc3.
Changes:
2.2.8:

* Fixed "inacccessible base" build errors with gcc 3.3.2. (Bradley Bell)
* win32: Re-enabled our wrappers for parts of the GTK+ API that are now properly
  exported on Windows by GTK+. See README.win32 for more details. (Cedric Gustin
)
* Documentation:
  - book:
    -Updated DrawingArea chapter for gtkmm2 (the last chapter that needed to be
updated)
      (Ainsley Pereira)
    - Mentioned Treeviews with popup menus, with example. (Murray Cumming)
    - The libglademm chapter has a clearer explanation of the memory management,
 and
      mentions the new get_widget_derived() method. (Murray Cumming)
  - Distribute doxygen tags for use by the documentation of related projects.
    (Bradley Bell)
  - Build and install a devhelp file for the reference docs. This doesn't
    work yet, but hopefully it's easy to fix. (roel@stack.be)