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/AtomicFlag.h

@@ -0,0 +1,121 @@
+//
+// AtomicFlag.h
+//
+// Library: Foundation
+// Package: Core
+// Module:  AtomicFlag
+//
+// Definition of the AtomicFlag class.
+//
+// Copyright (c) 2009, Applied Informatics Software Engineering GmbH.
+// and Contributors.
+//
+// SPDX-License-Identifier:	BSL-1.0
+//
+
+
+#ifndef Foundation_AtomicFlag_INCLUDED
+#define Foundation_AtomicFlag_INCLUDED
+
+
+#include "Poco/Foundation.h"
+#include <atomic>
+
+
+namespace Poco {
+
+
+class Foundation_API AtomicFlag
+	/// This class implements an atomic boolean flag by wrapping
+	/// the std::atomic_flag. It is guaranteed to be thread-safe
+	/// and lock-free.
+	///
+	/// Only default-construction is allowed, objects of this
+	/// class are not copyable, assignable or movable.
+	///
+	/// Note that this class is not a replacement for (atomic)
+	/// bool type because its value can not be read without also
+	/// being set to true. However, after being set (either
+	/// explicitly, through the set() call or implicitly, via
+	/// operator bool()), it can be reset and reused.
+	///
+	/// The class is useful in scenarios such as busy-wait or
+	/// one-off code blocks, e.g.:
+	///
+	/// class MyClass
+	/// {
+	/// public:
+	///     void myFunc()
+	///     {
+	///         if (!_beenHere) doOnce();
+	///         doMany();
+	///     }
+	///
+	///     void doOnce() { /* executed once */ }
+	///
+	///     void doMany() { /* executed multiple times */ }
+	///
+	/// private:
+	///     AtomicFlag _beenHere;
+	/// }
+	///
+	/// MyClass myClass;
+	/// int i = 0;
+	/// while (++i < 10) myClass.myFunc();
+{
+public:
+	AtomicFlag() = default;
+		/// Creates AtomicFlag.
+
+	~AtomicFlag() = default;
+		/// Destroys AtomicFlag.
+
+	bool set();
+		/// Sets the flag to true and returns previously
+		/// held value.
+
+	void reset();
+		/// Resets the flag to false.
+
+	operator bool ();
+		/// Sets the flag to true and returns previously
+		/// held value.
+
+private:
+	AtomicFlag(const AtomicFlag&) = delete;
+	AtomicFlag& operator = (const AtomicFlag&) = delete;
+	AtomicFlag(AtomicFlag&&) = delete;
+	AtomicFlag& operator = (AtomicFlag&&) = delete;
+
+	std::atomic_flag _flag = ATOMIC_FLAG_INIT;
+};
+
+
+//
+// inlines
+//
+
+
+inline bool AtomicFlag::set()
+{
+	return _flag.test_and_set(std::memory_order_acquire);
+}
+
+
+inline void AtomicFlag::reset()
+{
+	_flag.clear(std::memory_order_release);
+}
+
+
+inline AtomicFlag::operator bool ()
+{
+	return set();
+}
+
+
+} // namespace Poco
+
+
+#endif // Foundation_AtomicFlag_INCLUDED
+