(dired-recursive-copies): New custom variable.

(dired-recursive-copies): New custom variable.
(dired-handle-overwrite): Broke a long line.
(dired-copy-file): Call `dired-copy-file-recursive' instead of `copy-file'.
(dired-copy-file-recursive): New function.  Copy directories recursively.
(dired-do-create-files): Added support for generalized directory
target.  How-to function may now return a function.  New fluid
variable `dired-one-file'.
(dired-copy-how-to-fn): New variable.
(dired-do-copy): Bind `dired-recursive-copies' to preserve it.
Use dired-copy-how-to-fn as how-to argument to dired-do-create-files.
(dired-do-copy-regexp): No recursive copies.