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/Checksum.h

@@ -0,0 +1,108 @@
+//
+// Checksum.h
+//
+// Library: Foundation
+// Package: Core
+// Module:  Checksum
+//
+// Definition of the Checksum class.
+//
+// Copyright (c) 2007, Applied Informatics Software Engineering GmbH.
+// and Contributors.
+//
+// SPDX-License-Identifier:	BSL-1.0
+//
+
+
+#ifndef Foundation_Checksum_INCLUDED
+#define Foundation_Checksum_INCLUDED
+
+
+#include "Poco/Foundation.h"
+
+
+namespace Poco {
+
+
+class Foundation_API Checksum
+	/// This class calculates CRC-32 or Adler-32 checksums
+	/// for arbitrary data.
+	///
+	/// A cyclic redundancy check (CRC) is a type of hash function, which is used to produce a 
+	/// small, fixed-size checksum of a larger block of data, such as a packet of network 
+	/// traffic or a computer file. CRC-32 is one of the most commonly used CRC algorithms.
+	///
+	/// Adler-32 is a checksum algorithm which was invented by Mark Adler. 
+	/// It is almost as reliable as a 32-bit cyclic redundancy check for protecting against 
+	/// accidental modification of data, such as distortions occurring during a transmission, 
+	/// but is significantly faster to calculate in software.
+	
+{
+public:
+	enum Type
+	{
+		TYPE_ADLER32 = 0,
+		TYPE_CRC32
+	};
+
+	Checksum();
+		/// Creates a CRC-32 checksum initialized to 0.
+
+	Checksum(Type t);
+		/// Creates the Checksum, using the given type.
+
+	~Checksum();
+		/// Destroys the Checksum.
+
+	void update(const char* data, unsigned length);
+		/// Updates the checksum with the given data.
+
+	void update(const std::string& data);
+		/// Updates the checksum with the given data.
+
+	void update(char data);
+		/// Updates the checksum with the given data.
+
+	Poco::UInt32 checksum() const;
+		/// Returns the calculated checksum.
+
+	Type type() const;
+		/// Which type of checksum are we calulcating
+
+private:
+	Type         _type;
+	Poco::UInt32 _value;
+};
+
+
+//
+// inlines
+//
+inline void Checksum::update(const std::string& data)
+{
+	update(data.c_str(), static_cast<unsigned int>(data.size()));
+}
+
+
+inline void Checksum::update(char c)
+{
+	update(&c, 1);
+}
+
+
+inline Poco::UInt32 Checksum::checksum() const
+{
+	return _value;
+}
+
+
+inline Checksum::Type Checksum::type() const
+{
+	return _type;
+}
+
+
+} // namespace Poco
+
+
+#endif // Foundation_Checksum_INCLUDED