Accepts map parsing compiles with rfc2616.

The parsing inherited from Textpattern 4.5 does not
comply. The header can have multiple parameters and
tokens (parameters that do not have values).

This changes the parser so that it returns
multi-dimensional array, where the parameters are the
inner. Tokens will have value of TRUE.

git-svn-id: http://textpattern.googlecode.com/svn/development/4.x@5698 2fea6a4d-a838-0410-917b-93a53c48e9d2
Keep it as protected.

git-svn-id: http://textpattern.googlecode.com/svn/development/4.x@5699 2fea6a4d-a838-0410-917b-93a53c48e9d2