[O] [Feature Request] Provide a way to jump to noweb reference definition under point

[numbch...@gmail.com]

For example I have an Org buffer like this:

```org
#+NAME: define food-journal
#+BEGIN_SRC clojure
(def food-journal
  [{:month 1 :day 1 :human 5.3 :critter 2.3}
   {:month 1 :day 2 :human 5.1 :critter 2.0}
   {:month 2 :day 1 :human 4.9 :critter 2.1}
   {:month 2 :day 2 :human 5.0 :critter 2.5}
   {:month 3 :day 1 :human 4.2 :critter 3.3}
   {:month 3 :day 2 :human 4.0 :critter 3.8}
   {:month 4 :day 1 :human 3.7 :critter 3.9}
   {:month 4 :day 2 :human 3.7 :critter 3.6}])
#+END_SRC

#+BEGIN_SRC clojure
<<define food-journal>>

(take-while #(< (:month %) 3) food-journal)
#+END_SRC
```

The point is at `<<define food-journal>>`. Hope org-mode can provide and
shortcut to jump to noweb reference definition `#+NAME: define
food-journal`.

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