Forms return list of groupAddAssign function

@return A list with members savedGroupMembers, savedScore, and if withKin == TRUE groupKin as well.

groupMembersReturn(savedGroupMembers, savedScore, withKin, kmat)

Arguments

savedGroupMembers	selected animal group
savedScore	score of selected group, which is the group having the largest minimum group size
withKin	logical variable indicating to return kinship coefficients when TRUE.
kmat	numeric matrix of pairwise kinship values. Rows and columns are named with animal IDs.