Attempt to make the directories before trying to lock the lockfile.

In a fresh installation where the `.ini` file does not yet exist, the
application could wronly determine that another instance was running as
the lockfile could not be created due to the missing parent directory.

All the intermediate-level directories needed to contain the lockfile
are now created if they did not exist.

Source/GUI/Settings/SConfig.cpp

@@ -4,7 +4,9 @@
 #include <iostream>
 
 #include <qcoreapplication.h>
+#include <QDir>
 #include <qfile.h>
+#include <QFileInfo>
 
 namespace
 {
@@ -32,6 +34,7 @@ SConfig::SConfig()
   }
 
   const QString lockFilepath{m_settings->fileName() + "_lock"};
+  QDir().mkpath(QFileInfo{lockFilepath}.absolutePath());
   m_lockFile = std::make_unique<QLockFile>(lockFilepath);
   if (!m_lockFile->tryLock())
   {