We modified the function dist_make() to pass along additional arguments to
the distance function. This helps with distance functions that take extra
parameters. We removed the method keyword argument from dist_make() because
we found it not to be useful in practice.
We added a new function, dist_multi_centroid(), to produce a distance matrix
between multiple centroid positions.
We fixed an error in dist_groups() that will pop up in future versions of R.
In R 4.0.0, the data.frame() function will have a new default value,
stringsAsFactors = FALSE. This update caused one column in the output
from dist_groups() to change from a factor to a character vector, which broke
one of our tests. We updated the code to deliberately make this column a
factor. The function's behavior will be preserved when R 4.0.0 is released.