Use standard IO error code.  Value taken from EX_IOERR in sysexits.h.

Part of issue #1.
Extract data series used for testing.  Switch container type from list to tuple because tuples are immutable.
Add support for asserting that the last point in the data series is in control.  The assertion:
 * is activated via the new --assert-last-point-in-control command-line option
 * will cause the analyze_series command to exit with a status code of 2 when the last point is out-of-control, note that if the series has out-of-control points that are _not_ the last point the exist status will still be 0