Support finding references for a function named "fun"

[axelson]

From what I can tell it is possible to find references from a call, but you can't find references from the definition of a function.

So this works:

  test "working example" do
    buffer = """
    defmodule A do
      def a_fun do
        B.Callee.fun()
                  ^
      end
    end
    """

    references = ElixirSense.references(buffer, 3, 14)
    assert references != []
  end

But this does not:

  test "elixir-ls references test" do
    buffer = """
    defmodule B.Callee do
      def fun() do
           ^
        :ok
      end
    end
    """

    references = ElixirSense.references(buffer, 2, 7)
    assert references != []
  end

I'm trying to use ElixirSense.references/3 (elixir-lsp/elixir-ls#39) but need to be able to find the references for a function from it's definition (which I think makes sense from a usability standpoint as well).

[axelson]

This bug as originally worded was invalid so I'm just going to close in favor of the new bug I filed #42