More edits to Display chapter of Emacs manual.

More edits to Display chapter of Emacs manual.

* doc/emacs/display.texi (Fringes): Move overflow-newline-into-fringe here,
from Line Truncation node.
(Standard Faces): Note that only the background of the cursor face
has an effect.
(Cursor Display): Fix descriptions of cursor face
and bar cursor blinking.
(Text Display): Document nobreak-char-display more clearly.
(Line Truncation): Add xref to Split Window node.
(Display Custom): Don't bother documenting baud-rate or
no-redraw-on-reenter.

* doc/emacs/search.texi (Slow Isearch): Node removed.