Clarify that the opts passed are the default options for all requests.
Clarify that 'ropts' are the options passed to render.

It wasn't cler what "ropts" were. "Return options"? "Read-only options" ?

It appears that they are options to passed to render(), as opposed to the default options.
Clarify that 'filename' is the fifoFile.

'filename' is generic. The name 'fifoFile' clarifies that the filename
is question is the FIFO.
Clarify that pool refers to a pool of phantom processes.

When reviewing the code it wasn't clear whether this abstract pool was
made of requests, processes or what.

Using a more explicit name makes the code easier to understand.
Clarify what the 'queue' is for.

'queue' is a very generic. It wasn't clear before what it was a queue
of.

The updated name clarifies that's a queue of requests.
Remove stray debugging line added earlier.
Improve docs and diagnostics

- Generally, more code comments have been added.

- Child process stderr is now always piped to parent's stderr for
  better diagnostics.

  I didn't see any downside to this, but it's definitely useful when
  things aren't going well.

  It's also nice to not hide it behind a debug flag, since you don't
  always know when you are going to bump into a problem.

- New Troubleshooting section added to README, but note that
  it reflects how I updated the handling of STDERR for better
  diagnostics, and some commented out code I left in if
  people need super-deep diagnostics.
Add missing word to mkfifo docs and link to MIT license.
Fixes #23: Document supported output formats.

Updated some section headings to make room for the new docs.

Also noted that the authority for supported formats is Phantom, not us.
Merge branch 'issue-23-document-supported-formats'
Merge pull request #24 from markstos/issue-23-document-supported-formats

Supported output formats are now documented.
Add a little more detail to explain how the pool system works to README.md
Correct README.md-- you don't already have to have `phantomjs` installed

Since we depend on the `phantomjs` package.
Merge branch 'readme-corrections'
Merge pull request #25 from markstos/readme-corrections

Correct docs about phantomjs needing to be pre-installed.
Merge remote-tracking branch 'origin/master'
Tests should also use 'phantomjs' package for consistency.

The code has been updated to use the 'phantomjs' package to install and
locate the 'phantomjs' binary, but the tests has not.

If 'phantomjs' had install 'phantomjs' locally and 'phantomjs' was not
in $PATH, then the tests would fail, even though 'phantomjs' was
installed would be located by the code.

Now we test for phantomjs the same way the code would.
Merge branch 'test-should-use-phantomjs-package'
Merge branch 'test-should-use-phantomjs-package' into issue-20-support-args
Refactor: Consolidate default options in one place.

Previously, default options were scattered and checked throughout
the code. It was hard to see what all the options were, and there
were extra conditional checks because the code couldn't depend an option
already being set or not.

Now the all defaults are declared in one place, and some related
conditional code can be removed, since the code can now expect
the defaults to be set in advance.

(the phantomFlag support has not been introduced yet, but this lays the
foundation for it).