add chunking logic for more efficient large file reading

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MERRY HOLIDAYS!

This pull request does some things:

- defaults to `arraybuffer` for reads. this is because now with browserify 3 you can only write `Buffer` objects to streams
- because of this, it automatically converts ArrayBuffers into Buffers
- it also adds logic to read the file in chunks. this keeps the browser from crashing
- I think all types except `arraybuffer` are technically broken since they will cause errors when written to the outgoing stream. WHATEVS!

I tested it by dropping a entire folder full of mp3s onto a page and piping them over a single binary websocket to node, and it worked great!