Rework of lookahead access. Main function now
Parse_with_lexto support the separation of parsing
Performance improvement 'Array.replace'
Added function 'write_to_channel'
Changed signature of repetition combinators (e.g. 'one_or_more' and
Added a generic parsing combinator for parsing of operator expressions.
Complete rework of layout parsing.
Added functions to pretty print error messages and code snippets containing an
Documentation for parsing improved and augmented significantly.