Finishing the extension registry feature

[Jan-Oliver Wagner]

On Fri, Feb 18, 2005 at 06:17:30PM +0100, Bernhard Reiter wrote:
> We could also change both to use a magic function in the package.
> Doing this for registration first and then later for tests.
> 
> I tend to favour the magic function solution a little bit over the
> other, as we can later invent new magic functions for wx-dependent
> test or what ever without changing names all the time.

here is a improved approach. Less magic names and more
automization via callbacks.