Fix unconditional workspace dir recreation

With this commit creating of workspace dir is done *after* loading
of settings, so the workspace path from settings is taken into
account.

Previous behaviour was to create workspace dir before loading of
settings which led to path from settings to be ignored.

See comment:
 ra3xdh#145 (comment)

qucs/main.cpp

@@ -859,13 +859,13 @@ int main(int argc, char *argv[])
 
   // default
   QString QucsWorkdirPath = QDir::homePath()+QDir::toNativeSeparators ("/QucsWorkspace");
-  QDir().mkpath(QucsWorkdirPath);
   QucsSettings.qucsWorkspaceDir.setPath(QucsWorkdirPath);
   QucsSettings.QucsWorkDir.setPath(QucsSettings.qucsWorkspaceDir.canonicalPath());
 
   // load existing settings (if any)
   loadSettings();
 
+  QDir().mkpath(QucsSettings.qucsWorkspaceDir.absolutePath());
   QDir().mkpath(QucsSettings.tempFilesDir.absolutePath());
 
   // continue to set up overrides or default settings (some are saved on exit)