First release

In this release version, XPA provides the following functions.

1. You can do the qualify control on the dataset you provide and meanwhile, XPA will automatically match SNPs in main dataset and flip the minor allele accordingly.
2. You can compute the variance components and its standard deviation efficiently by method of moments.
3. You can do the cross-population analysis by specifying the option --geneticCorr. XPA will compute the genetic correlation and combine the information from two datasets.