hgweb: document continuereader Differential Revision: https://phab.mercurial-scm.org/D2767

hgweb: remove wsgirequest.__iter__ This was added in d0db3462d568 in 2006. I can't find a justification for this method in PEP 3333. I suspect we were originally intending to use this type as the WSGI application (which should be iterable)? The tests all pass without this method. So let's nuke it. Differential Revision: https://phab.mercurial-scm.org/D2749

hgweb: remove wsgirequest.read() This was just a proxy to self.inp.read(). This method serves little value. Let's nuke it. Callers in the wire protocol server have been updated accordingly. Differential Revision: https://phab.mercurial-scm.org/D2748

hgweb: remove unused methods on wsgirequest writelines() isn't used in our code base. close() was a no-op. It is an optional method per PEP 3333. My eventual goal is to kill the wsgirequest class, hence why I'm removing code. Differential Revision: https://phab.mercurial-scm.org/D2747