Neko enhancements

These are 2 minor changes to the HTTP client module.

I was not able to use the built-in HTTP client module in a project because the HTML that was returned by the HTTP requests had duplicate attributes in some elements. The first patch allows Neko not to throw in this case.

The second patch allows setting parser options for Neko for all following requests. At present, http:get-requests allow setting of options, all the other HTTP verbs are not so lucky. The addition of the set-options function rectifies this unhappy situation.

Of course there are other HTTP client packages, but I think these changes are unobtrusive and helpful enough to be included in the built-in package.