[bug] doesn't open files with option names

[averms]

If I have a file with -h as the name it won't open. The below patch fixes this problem.

diff --git a/xdg-open b/xdg-open
index a30b3ec..2a318df 100755
--- a/xdg-open
+++ b/xdg-open
@@ -73,7 +73,7 @@ fi
 
 if [[ -e "$arg" ]]; then
 	# file or dir
-	mime="$(file -ib "$arg" | cut -d';' -f1)"
+	mime="$(file -ib -- "$arg" | cut -d';' -f1)"
 	if [[ -f "$arg" ]]; then
 		ext="$(tr '[:upper:]' '[:lower:]' <<< "${arg##*.}")"
 	fi