qutebrowser: Make xdg-utils optional

Replace all hard-coded instances of using xdg-open with at least one
non-xdg alternative. Mostly falling back to either mimeo or a custom
open script.

qutebrowser/data/userscripts/wallabag_add.sh

@@ -12,6 +12,16 @@
 # Configure your wallabag instance with this:
 WALLABAG_INSTANCE="https://read.martyoeh.me"
 
+_open() {
+    if command -v open >/dev/null 2>&1; then
+        open "$1" &
+    elif command -v mimeo >/dev/null 2>&1; then
+        mimeo "$1" &
+    else
+        xdg-open "$1" &
+    fi
+}
+
 # only works for wallabag v2.*
 if [ "$#" -gt 0 ]; then
     BM="$WALLABAG_INSTANCE/bookmarklet?url=$*"
@@ -22,5 +32,5 @@ fi
 if [ -n "$QUTE_FIFO" ]; then
     echo "open -b -r $BM" >>"$QUTE_FIFO"
 else
-    xdg-open "$BM"
+    _open "$BM"
 fi