fitstats_optim: Goodness-of-fit Statistics
In philipshirk/nmmsims: Simulate & Analyze N-mixture Model Data

I based this function on "fitstats()" from https://github.com/rbchan/unmarked/blob/master/R/boot.R It's a function returning three goodness-of-fit statistics - sum-of-squares, Chi-squared, and the Freeman-Tukey test-statistic - calculated using my optim estimates rather than a model fit in "unmarked".

1	fitstats_optim(optim_out, n_obs, y_obs = NA, W, sampling_method)

`n_obs`	vector of observations at each site & replicate
`y_obs`	matrix of the number of observations in each distance category (from formatted unmarked data). Only used if sampling_method = "distance"
`W`	transect half-width (in meters)
`sampling_method`	either "pointcount" or "distance"
`out`	fit from optim