BF/NF microphone getRMSBins

- getRMS now uses numpy.std to avoid occasional error
changelogs
DEMO mental rotation

- classroom tested, works in single subjects
- illustrates using a temporary .csv file to save data
- parse data with pandas, display in a plot, print data suitable for copy &
  paste into a google-doc for group analysis
DEMO: improved user experience

- avoid full screen
- enable 'escape'
Merge pull request #426 from jeremygray/master

microphone loudness RMS; demo mental rotation