Problem: pathshorten() only supports using one character.
Solution: Add an argument to control the length. (closesvim/vim#7006)
6a33ef0deb
Cherry-pick a line in test from patch 8.2.0634.
Use Nvim's config paths in docs.
shorten_dir() returning a pointer looks a bit confusing here, as it is
actually the same pointer passed to it, and it doesn't really reduce
much code, so change it back to void.
Assigning rettv->vval.v_string = NULL is not needed if a pointer is
within 64 bits. While this is usually the case, I'm not sure if it can
be taken for granted.
d65ee12914
