Cookie header parser based on RFC6265 and RFC2109.

The parsing of cookies using RFC6265 is more relaxed that the specification in the following ways:

• Values 0x80 to 0xFF are permitted in cookie-octet to support the use of UTF-8 in cookie values as used by HTML 5.
• For cookies without a value, the '=' is not required after the name as some browsers do not sent it.

The parsing of cookies using RFC2109 is more relaxed that the specification in the following ways:

• Values for the path attribute that contain a / character do not have to be quoted even though / is not permitted in a token.

Implementation note:
This class has been carefully tuned to ensure that it has equal or better performance than the original Netscape/RFC2109 cookie parser. Before committing and changes, ensure that the TesterCookiePerformance unit test continues to give results within 1% for the old and new parsers.