get_out_prop: E step in EM algorithm for a single individual.
In dcgerard/updogAlpha: Using Parental Data for Offspring Genotyping

E step in EM algorithm for a single individual.

1 2	get_out_prop(ocounts, osize, ploidy, prob_geno, d, eps, tau, out_prop, out_mean, out_disp)

`ocounts`	The observed counts of the refernce allele for each individual.
`osize`	The observed number of reads for each individuals.
`ploidy`	An integer. The ploidy of the species. This is assumed to be the same for each individual.
`prob_geno`	The allele frequencies of the genotypes. See `get_prob_geno`.
`d`	The sequencing bias parameter.
`eps`	The sequencing error rate
`tau`	The overdisperion parameter.
`out_prop`	The proportion of points that are outliers. Defaults (quite arbitrarily) to `0.01`.
`out_mean`	The mean of beta-binomial for the outlier distribution. Defaults to `0.5`.
`out_disp`	The overdispersion parameter of the outlier distribution. Defaults to `1/3`, which corresponds to a uniform distribution for the underlying beta when `out_mean = 0.5`.