Add support for reporting histogram (density)

[rakhimov]

This modifies the "quantiles" schema to support bins
similar (but not the same) to the MEF input.
The distribution/frequency of the data is meant to be in the histogram
as a statistical measure for reporting.

It would be somewhat beneficial
if histogram reporting schema matched exactly
the input histogram-distribution (deviate) schema
since the semantics is the same.

[cfolleau]

From the result point of view, quantile are histograms (but with the same value for each interval since it is the definition).
If we want to be more general for the result provided by Motecarlo Simultation, histogram could replace quantile.
But if people want to keep the word "quantile" because it is more mathematically correct, no problem.

[rakhimov]

@cfolleau I think you are right.
I find both of them necessary/useful to calculate and report.
Correct me if I am wrong, but quantiles mask out the shape of the distribution.
The histogram derived from the quantiles is just boring flat line
with each bin having the same weight but different size;
Histograms, on the other hand, reveal the shape of the density.

[cfolleau]

yes exactly