df_to_kinpair: Convert dataframe or tibble to KinPairData class
Description
This function at minimum requires the dataframe to contain a column titled 'distance' containing distances
between kin pairs. It can optionally contain a column of kinship values 'kinship' as well as a column of lifestage values 'lifestage'.
If the file contains more than one value in the kinship or lifestage columns (e.g. bot 'FS' and 'HS') - the corresponding function
parameter must be set to pick a corresponding subset of dispersed pairs. where parameters are set in the absence of file columns,
these values are assigned to the returned KinPairData object.