test: Pass cli flags in pummel/test-regress-GH-892
stream: Increase highWaterMark on large reads

If the consumer of a Readable is asking for N bytes, and N > hwm,
then clearly we have set the hwm to low, and ought to increase it.

Fix #4931
stream: Remove pipeOpts.chunkSize

It's not actually necessary for backwards compatibility, isn't
used anywhere, and isn't even tested.  Better to just remove it.
stream: Remove bufferSize option

Now that highWaterMark increases when there are large reads, this
greatly reduces the number of calls necessary to _read(size), assuming
that _read actually respects the size argument.
stream: Allow strings in Readable.push/unshift

Fix #4909