Added

Group transform to introduce explicit groupings, now that parse values are flattened otherwise (see below).
Not parser to allow for negative look-ahead.
Forward declaration parser to allow for recursive rules.
BytesBuffer and parse_bytes for easier usage without asyncio streams.

Changed

Renamed the value property of ParseNode to values. All nodes return now iterables and sub-values will be flattened into a common iterable.
Renamed TransformValue to TransformValue as it now gets and is expected to produce an iterable of values.
Opt has no longer a custom implementation, but is just equivalent to expr[0, 1].

Fixed detection of EOF in streams to prevent parse_incremental from raising unexpected parse errors. The MockReader is now more closely matching the EOF behavior of StreamReader.
Fixed off-by-one error which could lead to a stalling reader waiting for a byte that never will be sent.