(midnight-time-float): Renamed from time-float.
(midnight-buffer-display-time): Renamed from buffer-display-time.
(midnight-mode): Specify :initialize. Use nil as default value.
(clean-buffer-list): Check `buffer-modified-p' only when the
buffer is associated with a file.
(midnight-delay-set): Improve doc.
(midnight-find): Don't use `find'.
(clean-buffer-list-kill-regexps): Match `*vc' buffers.
(midnight-find): Use dolist, not loop.
(clean-buffer-list-delay): Use assoc-default.
(assoc-default): New function.