fixed bug with the dimensions when method==rpc-based, apply_to==sign, cross_validation==TRUE and the correlation is not significant

Revised documentation and new sanity checks in functions CST_AdamontAnalog, AdamontAnalog, CST_AdamontQQCorr and AdamontQQCorr following expert review

Sorted the factor levels in the order required in the legend to avoid problems later. Reorganized ggplot calls.

added na.rm, apply_to and alpha parameters and their checks. Changed na.rm=T for na.rm=na.rm everywhere. Added documentation.