(wdired-mode-map): Move init into declaration. Fix `return' binding.

(wdired-mode-map): Move init into declaration.  Fix `return' binding.
(wdired-change-to-wdired-mode, wdired-change-to-dired-mode):
Use force-mode-line-update.
(wdired-get-filename): Use `unless'.
(wdired-preprocess-files): Don't assume names have no \n and use / for dirsep.
(wdired-normalize-filename): Use replace-regexp-in-string.
(wdired-load-hooks): Remove.
(wdired-mode-hooks): Rename to wdired-mode-hook.