Fix not working LaunchExternal() on Linux on wxWidgets 3.1.4

Adding quotes breaks the path actually used to run the browser.
However they are needed on wxWidgets 3.0

common/launch_ext.cpp

@@ -34,8 +34,14 @@ void LaunchExternal( const wxString& aPath )
     system( msg.c_str() );
 #else
     wxString path( aPath );
+
+#if !wxCHECK_VERSION( 3, 1, 0 )
     // Quote in case there are spaces in the path.
+    // Not needed on 3.1.4, but needed in 3.0 versions
+    // Moreover, on Linux, on 3.1.4 wx version, adding quotes breaks
+    // wxLaunchDefaultApplication
     AddDelimiterString( path );
+#endif
 
     wxLaunchDefaultApplication( path );
 #endif