Function name parsing can't handle special chars

[GB609]

Bash allows almost any utf-8 character as part of a function name.

Shdoc currently only handles/allows [a-zA-Z0-9_\-:-\\.]+ which appears to be:

• all lower ascii letters
• all upper ascii letters
• all digits
• _, -, .
• the range between : - \
  This is strange because it includes all uppercase letters and only a handful of special characters ;<=>?@[, ; in fact even leads to a syntax error.
  The - between : and \\ rather appears to be a coding error.

It might be better to replace the positive matching with a negation of the disallowed characters, which are \()&|;.