GH-885 export dialog for filtering exported files

Includes implementation of a separator based prefix tree and some related bits

logic/MMCStrings.h

@@ -0,0 +1,8 @@
+#pragma once
+
+#include <QString>
+
+namespace Strings
+{
+	int naturalCompare(const QString &s1, const QString &s2, Qt::CaseSensitivity cs);
+}