Two small, independent units, split along the lines Java and .NET draw:
Security.Crypto SHA-1 (raw 20-byte digest + Sha1Hex), the home for hash
digests (cf. java.security / System.Security.Cryptography).
Encoding.Base64 Base64 encode + decode (RFC 4648), a general text encoding,
not crypto (cf. java.util.Base64 / System.Convert).
Callers compose them, e.g. the WebSocket handshake is
Base64Encode(Sha1(key + GUID)). Both TStringBuilder-backed (O(n)).
Adds Crypto.Tests (SHA-1 FIPS vectors + the RFC 6455 handshake) and
Base64.Tests (RFC 4648 vectors, decode, round-trip) to the stdlib test tree
via Test.Registry; pasbuild test -m blaise-stdlib runs 27 tests.
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