(Fringes): Rewrite previous change.

(Fringes): Rewrite previous change.
(Fringe Bitmaps): Merge text from Display Fringe Bitmaps.  Rewrite.
(Display Fringe Bitmaps): Node deleted, text moved.
(Customizing Bitmaps): Split off from Fringe Bitmaps.  Rewrite.
(Scroll Bars): Clarify set-window-scroll-bars.
(Pointer Shape): Rewrite.
(Specified Space): Clarify :align-to, etc.
(Pixel Specification): Use @var.  Clarify new text.
(Other Display Specs): Clarify `slice'.
(Image Descriptors): Cleanups.
(Showing Images): Cleanups.