Commit of some improvements when running under Cygwin

* musredit can now be built using Qt 4.5.3 of Cygwin 1.7---however, without online help
* FFTW3 threading in some user functions has been disabled

Obviously, there is a major problem when running musrgui/musredit with Cygwin on Windows7/64bit.
This has not been solved by this commit!

src/musredit/PHelp.cpp

@@ -44,6 +44,7 @@
  */
 PHelp::PHelp(const QString &url)
 {
+  #ifndef _WIN32GCC
   fProgress = 0;
 
   QNetworkProxyFactory::setUseSystemConfiguration(true);
@@ -71,6 +72,7 @@ PHelp::PHelp(const QString &url)
 
   setCentralWidget(fView);
   setUnifiedTitleAndToolBarOnMac(true);
+  #endif // _WIN32GCC
 }
 
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