Enable CalibrateRectangularDetetors to calibrate a subset of detectors

[wdzhou]

This issue was originally TRAC 7349

For POWGEN's K4, some spectra have enough number of counts to fit peaks by themselves. But many of them won't be able to do that unless they are summed together. So it is helpful to use different approaches to calibrate these detectors.

Besides, it can also improve the fitting of offset on detector covers low-d (high-Q) range. These detectors have enough counts on them but most of peaks outside of boundary.

[wdzhou]

@NickDraper (2013-07-26T14:01:43):
Moved to the Backlog after R2.6

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@NickDraper (2014-02-14T11:04:54):
Bulk move to assigned at the introduction of the triage step

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