Methods for error estimation of blended and smoothed indexes about hpir HOT 2 CLOSED

This is going to require some major reorganization as the error methods are all quite different.

Also many directly access hpi_obj$index which would need to become more flexible.

Smoothing side of this is much easier to accomplish (probably with addition of a few extra arguments to calcAccuracy(). I suspect that the blending version will need a special wrapper function.

At the core of this the Error Calculations (and maybe all of the index analytics) need to become more standardized.

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Closing as the smoothed index version is complete.

Moving the blending version to #45

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