calculate PRSs in Lifelines using SBayesRC

Due to the rapid development of genome-wide association studies (GWAS), polygenic risk scores (PRS) for common diseases are playing increasingly important roles in research and medical applications. PRSs are used to identify individuals with high genetic risk of complex diseases which provides opportunities for early intervention, improved prognosis and personalised treatment. Also PRS can facilitate gene-environment interaction study,  and help to explore putative causal relationships between traits.