Show a warning if the instance path contains a '!'

The checks and warnings happen the time MMC loads (via QLOG_INFO), the time the GUI starts (via a dialog) and when the user changes the instance path via the settings window.

depends/util/include/pathutils.h

@@ -16,6 +16,7 @@
 #pragma once
 
 #include <QString>
+#include <QDir>
 
 #include "libutil_config.h"
 
@@ -57,3 +58,6 @@ LIBUTIL_EXPORT void openFileInDefaultProgram(QString filename);
 
 /// Opens the given directory in the default application.
 LIBUTIL_EXPORT void openDirInDefaultProgram(QString dirpath, bool ensureExists = false);
+
+/// Checks if the a given Path contains "!"
+LIBUTIL_EXPORT bool checkProblemticPathJava(QDir folder);