QNetworkAccessManager which is used for all network traffic does not
automatically recover from network outages. This patch tries to
reestablish network accessibility before any requests are attempted.
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@6471 ab8295b8-cf94-4d9e-aec4-7959e3be5d79