Fix sxiv invocation

The file name has to be the last argument. It was causing the following
errors:

    sxiv: -N: No such file or directory
    sxiv: fontpreview: No such file or directory
    sxiv: -b: No such file or directory

 fontpreview | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fontpreview b/fontpreview
index 3d2ce80..f9595f0 100755
--- a/fontpreview
+++ b/fontpreview
@@ -124,7 +124,7 @@ main(){
 	    if  [ ! -e /proc/$PID ] ; then
 		echo "Restart sxvi - You maybe using a obsolete version. " >&2
 		# Display the font preview using sxiv
-		sxiv -g "$SIZE$POSITION" "$FONT_PREVIEW" -N "fontpreview" -b &
+		sxiv -g "$SIZE$POSITION" -N "fontpreview" -b "$FONT_PREVIEW" &
 
 		# Change focus from sxiv, back to the terminal window
 		# so that user can continue to search for fonts without