Add a new trait to the simulation.
a new object descended from
LociMap-class
the value for varA in the base population, optional
the value for varG in the base population, optional
default error variance for phenotype, optional
should the check for a running simulation be ignored. Only set to TRUE if you know what you are doing
SP$manAddTrait(lociMap, varA = NA_real_, varG = NA_real_, varE = NA_real_, force = FALSE)