#13 Move to sigc++-2.0/ gtkmm-2.4

[Gert Wollny]

This patch makes gcdmaster compile with the new
interfaces provided by sigc++-2.0, gtkmm-2.4, and
libgnomeuimm-2.6.
It is not tested whether it breakes compatibility with
sigc++-1.2 and gtkmm < 2.4. To get the port compile I
had to disable the AudioCDView::drag_data_received_cb
callback (but appearently it didn't do anything yet),
and the AutoCDProject::Toolbar2() method which is also
not used (as far as I can see) .

[Gert Wollny]

Patch against cdrdao-1.1.8

[Denis Leroy]

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Patch has been applied to gtkmm24 branch. Thank you. Most
likely will be part of future 1.2.0 release.