nadiv dependency

[joelpick]

nadiv is currently not on CRAN, so need to install from github first e.g. with
library(remotes); install_github("matthewwolak/nadiv", ref = "devel")

need to update to remove this dependency at least in short term but seems nadiv will be back on cran at some point soon. Currently it is used for simulation of dominance and epistatic effects

[joelpick]

nadiv dependency has been removed, but some functionality is lost. when its back on cran, will reinstate this