Added warning and error messages when the size of the study is larger than the study of the population and when the study is not a subset of the background population. This could be do to file swaps or to un matching identifiers.
Added warning and error messages when the size of the study is larger than the study of the population and when the study is not a subset of the background population. This could be do to file swaps or to un matching identifiers.

tanghaibao/goatools,mfiers/goatools,mfiers/goatools,fidelram/goatools,fidelram/goatools,lileiting/goatools,tanghaibao/goatools,lileiting/goatools