(isearch-fail): Use "RosyBrown1" for a light

(isearch-fail): Use "RosyBrown1" for a light
background, "red4" for a dark background, "red" for 16 and
8 colors, "grey" for grayscale, and inverse video otherwise.
Add :version tag.
(isearch-message): Keep the original isearch-message intact, and
add text properties to it where necessary.  Add `isearch-error' to
the condition that checks if isearch is unsuccessful.