[whatwg] API for encoding/decoding ArrayBuffers into text

[Joshua Bell]

FYI, I've updated http://wiki.whatwg.org/wiki/StringEncoding

* Rewritten in terms of Anne's Encoding spec and WebIDL, for algorithms,
encodings, and encoding selection, which greatly simplifies the spec. This
implicitly adds support for all of the other encodings defined therein - we
may still want to dictate a subset of encodings. A few minor issues noted
throughout the spec.
* Define a "binary" encoding, since that support was already in this spec.
We may decide to kill this but I didn't want to remove it just yet.
* Simplify methods to take ArrayBufferView instead of
any/byteOffset/byteLength. The implication is that you may need to use
temporary DataViews, and this is reflected in the examples.
* Call out more of the big open issues raised on this thread (e.g. where
should we hang this API)

Nothing controversial added, or (alas) resolved.