fixed match() to prefer prefix-matches to strstr-matches in the match list, extended the -y handling, next version is 3.6

dmenu.1

@@ -26,7 +26,9 @@ efficiently.
 defines the x coordinate dmenu appears at (0 by default).
 .TP
 .B \-y
-defines the y coordinate dmenu appears at (0 by default).
+defines the y coordinate dmenu appears at (0 by default). If it is negative,
+dmenu will appear with the bottom at the given positive coordinate. It it is
+-0, dmenu appears at the screen bottom.
 .TP
 .B \-w
 defines the width of the dmenu window (screen width by default).