take rerp_parfor out of dependencies
Fix artifact indexes transfer
Make regression more robust
Enforce positive lambda
Enhance legend to have significance marker
fix bugs from empty profile and results folders
documentation
Implementing changes to facilitate group analysis
Implement weighted averaging for R2

weights are based on number of samples used to compute the R2 estimate.
Becomes important when doing cross validation on individual event types
since a given cross validation fold may have many more samples than the
others, or no samples at all.
Implement group level combined average total R2
Create functions for weighted t-test
create class for cross-validation folds
Integrate weighted t-test and RerpXvalFolds class
Add group level plotting for R2 plots
Make R2 plots look nicer
Make result gui more user friendly
Fix indexing bug