[web-audio-api] Propose additions to AnalyserNode for getting complex data (#262)

This proposal, based on the feedback[1] on the public-audio mailing
list, adds two methods to get the complex (real and imaginary) values of
the frequency data calculated in the `AnalyserNode`.


[1] http://lists.w3.org/Archives/Public/public-audio/2013JulSep/1925.html
You can merge this Pull Request by running:

  git pull https://github.com/chrislo/web-audio-api proposed-complex-api-analyzernode

Or you can view, comment on it, or merge it online at:

  https://github.com/WebAudio/web-audio-api/pull/262

-- Commit Summary --

  * Propose get(Float|Byte)ComplexFrequencyData
  * Clarify get(Float|Byte)FrequencyData returns magnitude

-- File Changes --

    M index.html (62)

-- Patch Links --

https://github.com/WebAudio/web-audio-api/pull/262.patch
https://github.com/WebAudio/web-audio-api/pull/262.diff