pub fn name_files(
files: &[String],
existing: &HashSet<String>,
how: Collision,
) -> Vec<String>Expand description
Chooses the names for files copied into one directory that already
holds existing (lower-cased). Names are compared ignoring case. A name
used once, and free, is kept. Otherwise every file of that name is
numbered, as Eagle does: a.png twice becomes a-1.png and a-2.png;
with KeepBoth, an a.png already there counts as the first, so a new
one becomes a-2.png. A numbered name that is taken is skipped.