helper/extension methods, composition, cleanups and fixes

- ADD: ReadGuid() helper & extension methods for BinaryReader
- ADD: WriteGuid() helper & extension methods for BinaryWriter
- ADD: ComposablePartCatalog based on an assembly public key whitelist
- ADD: optimized version of SequenceEqual() extension method for older
.NET target frameworks
- CHG: code cleanups
- FIX: compiler errors