add support for other HTTP methods

[Conal-Tuohy]

Prompted by the recent updates to the XProc 3.0 issue about HTTP methods, where I argued that an XProc processor should support any method, I finally got around to the refactoring we discussed a while back, when I had quickly patched in HTTP PATCH.

I've added two inner classes to implement HTTP requests with a body, and without a body, which are used when the c:request/@method is not one of the specifically-handled methods like GET and PUT. If you supply a body, you get one of those classes; if you don't supply a body, you get the other.

I "flipped" the sanity check which used to ensure that you didn't supply a body along with a method which doesn't call for a body, so that it uses an "open world" assumption, and rejects only the cases which it knows are definitely in error, and otherwise (if the method is not known) it assumes that you know what you're doing.

The additional tests make HTTP OPTIONS requests, both with and without a body, and check that the server responds with 200 OK to both.

[Conal-Tuohy]

@ndw, if you have a moment? I don't think this is at all controversial, and I'd love to see it accepted, so that I'm not continuing to use a fork of your codebase.

Also it would be great if you'd consider taking the same approach to dealing with unknown HTTP methods in the new version of Calabash.

[ndw]

Applied to version 1.2.5 for Saxon 9.9 and Saxon 10.x