internal/cmpimg: export as gonum.org/v1/plot/cmpimg
Comparing plot outputs (PNG, PDF, JPG, ...) for tests is useful not only in gonum/plot
but also for clients using gonum/plot
, outside of this repository.
we should consider exporting gonum.org/v1/plot/internal/cmpimg
.
perhaps simply as gonum.org/v1/plot/cmpimg
?