wxGTK cleanup

[Joerg Sonnenberger <joerg%britannica.bec.de@localhost>]

Hi all,
I would like to finally cut down the number of wxGTK versions in our
tree. For wxGTK 2.4, only one user remains (games/wxhugo) and that
package seems to be completely unmaintained.

For wxGTK 2.6, only x11/wxhaskell and converters/tex2rtf remain. The
former doesn't build against at least modernish GHC. The latter seems to
have been a contributed example program for wxWidgets and at least the
home page no longer exists.

Joerg