Put goto-line paths in the margin

Moreover, get rid of funky backgrounds (such as visible marks and
such)

avy.el

@@ -1032,12 +1032,19 @@ COMPOSE-FN is a lambda that concatenates the old string at BEG with STR."
            `(face ,(overlay-get other-ol 'face)) old-str))
         (overlay-put ol 'window wnd)
         (overlay-put ol 'category 'avy)
-        (overlay-put ol (if (eq beg eob)
-                            'after-string
-                          'display)
-                     (funcall
-                      (or compose-fn #'concat)
-                      str old-str))
+        ; here i should write in the margin IF I am doing at the bol
+        (if (eq avy-command 'avy-goto-line)
+            (let ((str-margin (concat " " str)))
+              (add-face-text-property 0 (length str-margin) `(:background ,(face-attribute 'default :background)) nil str-margin)
+              (overlay-put ol 'before-string
+                           (propertize str 'display
+                                       `((margin left-margin) ,str-margin))))
+          (overlay-put ol (if (eq beg eob)
+                                'after-string
+                              'display)
+                         (funcall
+                          (or compose-fn #'concat)
+                          str old-str)))
         (push ol avy--overlays-lead)))))
 
 (defcustom avy-highlight-first nil