Tests: move Excel tests to correct namespace
Interpolation: upgrade remaining algorithms accordingly
Interpolation: api cleanup
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