Disable '-warn-error' for library code
Added Pearson and Spearman correlation to 'Pareto.Sample' -- closes #16
Added a note on ties strategy in 'Correlation.spearman'
Merge pull request #17 from nrlucaroni/master

Added running statistics module from #12, thanks @nrlucaroni!
Cleaned up 'Sample.Summary' -- thanks @nrlucaroni!
Moved 'autocorrelation' to 'Sample.Correlation.Auto' and removed 'autocovariance'