* removed internal upper limit on word/string length for parsed input.

  - Although it has not caused many problems, no reason to retain
    these limits.
  - simplify some of the internal logic for reading string-like items.
  - localize parsers for better separation from the header

  - expose new function seekCommentEnd_Cstyle(), as useful
    handler of C-style comments

* exclude imbalanced closing ')' from word/variable

  - previously included this into the word/variable, but makes more
    sense to leave on the parser for the following token.

    Prevents content like 'vector (10 20 $zmax);' from being parsed
    as '$zmax)' instead of as '$zmax' followed by a ')'.
    No conceivable reason that the former would actually be desirable,
    but can still be obtained with brace notation: Eg, '${zmax)}'

* consistent handling of ${{ ... }} expressions

  - within a dictionary content, the following construct was
    incorrectly processed:

        v...