Reimplemented/streamlined SymmetricCryptoStream. Much cleaner now.
Implemented HashStream and some related DTO classes for the purposes of widening the selection of key confirmation methods (now not just KDFs).

KeyConfirmation DTO object renamed to VerificationFunction so as to widen its usable scope.

Added base functions to DecoratingStream, and an Erase/Reset function to RingByteBuffer.