Major plugin refactor and cleanup.

Switched to POCO library for unified platform/library interface.
Deprecated the external module API. It was creating more problems than solving.
Removed most built-in libraries in favor of system libraries for easier maintenance.
Cleaned and secured code with help from static analyzers.

vendor/POCO/Foundation/include/Poco/OrderedSet.h

@@ -0,0 +1,48 @@
+//
+// OrderedSet.h
+//
+// Library: Foundation
+// Package: Core
+// Module:  OrderedSet
+//
+// Definition of the OrderedSet class template.
+//
+// Copyright (c) 2012, Applied Informatics Software Engineering GmbH.
+// and Contributors.
+//
+// SPDX-License-Identifier:	BSL-1.0
+//
+
+
+#ifndef Foundation_OrderedSet_INCLUDED
+#define Foundation_OrderedSet_INCLUDED
+
+
+#include "Poco/Foundation.h"
+
+
+#ifdef min
+#undef min
+#endif
+#ifdef max
+#undef max
+#endif
+#include "Poco/ordered_hash.h"
+#include "Poco/ordered_set.h"
+
+
+namespace Poco {
+
+
+template<class Key,
+		class Hash = std::hash<Key>,
+		class KeyEqual = std::equal_to<Key>,
+		class Allocator = std::allocator<Key>,
+		class ValueTypeContainer = std::deque<Key, Allocator>>
+using OrderedSet = tsl::ordered_set<Key, Hash, KeyEqual, Allocator, ValueTypeContainer>;
+	/// For documentation, see https://tessil.github.io/ordered-map/
+
+} // namespace Poco
+
+
+#endif // Foundation_OrderedSet_INCLUDED