[cperl-mode] minor highlighting deficiencies

[LanX <lanx.perl@googlemail.com>]

Hi

1) UNITCHECK blocks aren't treated like CHECK blocks i.e. `font-lock-
keyword-face'

2) Highlighting of variables in strings are not consistent
  a) in $a="@a %h $s";
   the arrays and hashes are highlighted the scalars are not (`font-
lock-string-face')

  b) there is no difference between single and double quoted
(interpolated) strings.
     $a='@a %h $s';

  c) escaping doesnt change the highlighting of arrays and hashes
     $a="\@a \%h \$s";

3) Variablegrouping in braces are not discovered
    print @{a} %{h} ${s};

    while it's disputable if the identifieres within the braces are
easily parsed,
   since  @{$array_ref} is a dereferencing command, it could be at
least suggested
   to highlight the surrounding  @{ ...} in cperl-array-face or at
least
   perl-nonoverridable-face like in constructs like qq{...}

4) perl allows whitespaces between sigils and identifier, i.e. @ a and
@ {a} are legal
   arrays ... while I wouldn't say it's good style.


All of these suggestions except the first one need quite complicated
look around parsings, as a minimal solution it should be considered at
least to skip variable highlighting within strings, like they are
ignored in scalar variables.

Cheers
  Rolf