Internal helper that filters a plot data frame to the weight range given by
wlim. It is exported so that extension packages (such as mizerMR) can reuse
it in their own array plot() methods.
apply_wlim(data, wlim)The subset of data with w inside wlim.
A data frame with a numeric w column.
A length-2 numeric vector giving the lower and upper weight
limits. Either entry may be NA to leave that side unrestricted.