calc example exits cleanly on end of input
Fix crash when rtrl is given a grammar without a "grammar"
declaration.
%no-whitepsace directive

This directive cancels the %whitespace directive, either globally, or
limited to a block.  The use case is a grammar which is almost
entirely whitespace insensitive, except for a few rules.  Such a
grammar can now be:

    %whitespace SPACE*

    # many whitespace insensitive rules

    %no-whitespace

    # a few whitepsace sensitive rules

Or, alternatively:

    %whitespace SPACE*

    # many whitespace insensitive rules

    %no-whitespace {
      # a whitespace insensitive rule
    }

    # more whitespace insensitive rules
character sequence

A character sequences matches text a character at a time, exactly as
if each character had been specified separately in a sequence.  This
allows whitespace to be skipped between the characters of a literal,
provided that a %whitespace directive is in effect.

A character sequence is written like `%c"..."` or %c'...'`.  The "c"
stands for "characters."

The character sequence:

    %c"THEN"

is equivalent to

    ("T" "H" "E" "N")

Most of the time, you probably want a string literal.  Character
sequence exists for strange languages like BASIC and Fortran, which
permit whitespace in keywords.
Fix typo in feature comments
Correct typo in docs
Warning about textual substitution of labels
Merge pull request #3 from wconrad/calc-example-exits-cleanly-on-eof

calc example exits cleanly on end of input
Merge pull request #5 from wconrad/fix-ratl-crash-when-grammar-declaration-missing

Fix rtlr crash when no "grammar" declaration
Merge pull request #6 from wconrad/no-whitespace-directive

%no-whitepsace directive
Merge pull request #9 from wconrad/warn-about-textual-substitution-of-labels

Warn about textual substitution of labels in normal semantic nodes
Merge pull request #7 from wconrad/character-sequence

character sequence