Parser should be less strict about attribute arguments

[nevans]

The prism parser (the only parser since v8.0.0) is strict about arguments to attr_reader, attr_writer, attr_accessor, and attr. It only parses as an attribute when all arguments are symbols.

As an example, the rdoc for Net::IMAP::Config intentionally took advantage of the looser parsing done by rdoc 7.2. Net::IMAP::Config defines its own versions of attr_reader, attr_writer and attr_accessor that add keyword arguments.

For example:

      # Seconds to wait until a connection is opened.
      #
      # Applied separately for establishing TCP connection and starting a TLS
      # connection.
      #
      # If the IMAP object cannot open a connection within this time,
      # it raises a Net::OpenTimeout exception.
      #
      # See Net::IMAP.new and Net::IMAP#starttls.
      #
      # The default value is +30+ seconds.
      attr_accessor :open_timeout, type: Integer, default: 30

rdoc 7.2 simply ignores the unknown keyword args, and parses this no differently from attr_accessor :open_timeout.

In my opinion, this is a bug in rdoc 8.0 which should be fixed.