Addresses #50 and #3347 (ScheduleFile)

[joseph-robertson]

Design docs:

• [ScheduleFixedInterval] https://docs.google.com/document/d/1yduODStocC_zFRrxN-ZHLtzov1X7EqVYGNX9T0DkdQU/edit#heading=h.oqu01h6gsn2x
• [CSVFile] https://docs.google.com/document/d/1fnsSmmPnXgMBsB0WiHd_mpszKyzSI8BSAl-6fFGZBcQ/edit#

TODO:

• [Dan] Write CSVFile class and methods
• [Joe] Optionally call this class in FT for Schedule:FixedInterval
• [Joe] Test reverse translation of Schedule:File (unit test, OSApp, etc.)
• [Joe] Write more tests for CSVFile addColumn and getColumn methods
• [Joe] ScheduleFile::csvFile that returns CSVFile
• [Joe] Think about multiple schedulefixedintervals in one csv [meh; sounds rough...]
• [Joe] Add regression tests corresponding to FT (false, true)

[shorowit]

@macumber @joseph-robertson Thanks for making this optional and defaulting to No.