Percentile: Bug fixes and compliance with Excel.

High boundary check was against 100, should be 1.0.
Close to 0 or 1 percentile values for Nist and Interpolation methods
caused array out of bounds exceptions.
Seemingly arbitrary small dataset restriction removed.
Out of range percentile values and empty dataset returns double.NaN
instead of throwing, similar to Excel returning #NUM! in such cases.
Statistics: cosmetics
Statistics: introduce SortedArrayStatistics, use it in Percentile class
Statistics: add min, max, percentile, quaritle, iqr, fivenum to sorted-array stats
Statistics: introduce unsorted ArrayStatistics
Statistics: sample/unibiased variance of empty set should be NaN #101
Statistics: introduce StreamingStatistics, always throw on null data
Statistics: never throw on empty data (instead use NaN)
Statistics: extending tests and cosmetics
Statistics: Streaming Mean
Statistics: mean of empty set should be NaN
Statistics: Array and Streaming Variance
Statistics: Array and Streaming PopulationVariance
Statistics: Array and Streaming Sample and Population StandardDeviation
Statistics: Proper Quantile statistics (supporting all 9 R-types and custom)