close ZeroConf object when exiting the Service Discovery window.
(otherwise pythonw.exe does not exit when closing Beremiz on Windows)
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<font size="3">Beremiz is an Open Source framework for automation.</font>
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<a href="http://www.beremiz.org/">http://www.beremiz.org/</a>
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University of Porto<BR>
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Supported by :
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LOLITech<BR>
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