Tests: move Excel tests to correct namespace
Interpolation: upgrade remaining algorithms accordingly
Interpolation: api cleanup
Fixed comment in TriangularDistribution example

The <summary> tag of the TriangularDistribution class read "ContinuousUniform distribution example". It now reads "Triangular distribution example".
Statistics: Ranks
Statistics: quantile rank, empirical CDF, Excel percentrank
Statistics: s/InverseCDF/EmpiricalInvCDF/
Update contributing.md with more details about primary and secondary project files
Build: include .Net 3.5 build in NuGet package
Update release notes, contributors
Distributions: static PDF/CDF functions for StudentT, Stable, Weibull #188
Distributions: switch default RNG from MersenneTwister to SystemRandomSource
LA, Statistics, Generate: switch default RNG from MersenneTwister to SystemRandomSource
Tests: adapt tests to different data from new RNG (system instead of MT)
Generate: new variants with fast RandomUniform
Distributions: drop redundant xmldoc remarks. Closes #183.
Build: update supported platforms in NuGet nuspec descriptions
Distributions: StudentT.InvCDF
Distributions: Beta.InvCDF
ExcelFunctions: BETADIST, BETAINV, TINV