Version 3.6.0

• [Breaking Changes]
  • CipherlibConverter -> BitConverter (the exported bit-converter base class).
  • BigIntDecoder narrows from Converter<BigInt, Iterable<int>> to
    Converter<BigInt, Uint8List>; BigIntCodec decoders now return a Uint8List.
• Export the ByteEncoder, ByteDecoder, AlphabetEncoder, and AlphabetDecoder
  base classes, previously part of the API surface but not reachable through
  package:convertlib/convertlib.dart.
• Add constantTimeEquals, a top-level constant-time byte comparison for
  verifying MACs and digests without wrapping them in a ByteCollector.
• Add toHexBytes, toBinaryBytes, toOctalBytes, toBase32Bytes, and
  toBase64Bytes, returning the encoded ASCII output as a Uint8List without
  the intermediate String.
• Add non-throwing decoders tryFromHex, tryFromBinary, tryFromOctal,
  tryFromBase32, tryFromBase64, tryFromUtf8, and tryFromBigInt, which
  return null instead of throwing a FormatException on invalid input.
• Fix the UTF-8 encoder emitting invalid bytes for scalar code points in
  U+10000..U+10FFFF; UTF8Encoder.convert now uses the 4-byte form (the public
  toUtf8 was unaffected). Verified against dart:convert.
• Make the Crockford Base-32 decoder case-insensitive and decode the ambiguous
  letters I/i/L/l as 1 and O/o as 0. Encoding output is unchanged.
• Fix ByteCollector.number truncating values wider than 32 bits on the web; it
  now accumulates with multiplication and is exact up to 2^53 (VM unchanged).
• ByteCollector.isEqual returns false for a [String] that is not valid
  hexadecimal instead of throwing a FormatException, matching its contract.
• Add value-based == and hashCode to CryptData; a null and an empty
  params map now compare equal (both encode to the same string).
• PHC/crypt: allow empty parameter values (e.g. $id$data=), and fix the decoder
  mis-classifying a comma-containing v=... segment as the version.
• Speed up fromBase32/fromBase64 decoding and the generic AlphabetEncoder by
  removing extra allocations and passes; output is byte-identical.
• Clarify the FormatException message for non-canonical encoded input:
  'Invalid length' is now 'Invalid length or non-zero trailing bits'.

Full Changelog: v3.5.1...v3.6.0