Add support for Zipper.find_all/3 - #163

  1) test get_range/1 bitstrings (SourcerorTest.RangeTest)
     test/range_test.exs:1041
     Assertion with == failed
     code:  assert decorate(code, to_range(code)) == "«<<1, 2,\n\n foo>>»\n" |> String.trim_trailing()
     left:  "«<<1, 2,\n\n foo>>\n»"
     right: "«<<1, 2,\n\n foo>>»"
     stacktrace:
       test/range_test.exs:1051: (test)

......

  2) test get_range/1 anonymous functions (SourcerorTest.RangeTest)
     test/range_test.exs:664
     Assertion with == failed
     code:  assert decorate(code, to_range(code)) == "«fn ->\n  :ok\nend»\n" |> String.trim()
     left:  "«fn ->\n  :ok\nend\n»"
     right: "«fn ->\n  :ok\nend»"
     stacktrace:
       test/range_test.exs:674: (test)

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  3) test get_end_position/2 returns the correct positions (SourcerorTest)
     test/sourceror_test.exs:546
     Assertion with == failed
     code:  assert Sourceror.get_end_position(quoted) == [line: 3, column: 1]
     left:  [line: 3, column: 3]
     right: [line: 3, column: 1]
     stacktrace:
       test/sourceror_test.exs:565: (test)

.

  4) doctest Sourceror.get_end_position/2 (20) (SourcerorTest)
     test/sourceror_test.exs:7
     Doctest failed
     doctest:
       iex> quoted = ~S"""
       ...> foo do
       ...>   :ok
       ...> end
       ...> """ |>  Sourceror.parse_string!()
       iex> Sourceror.get_end_position(quoted)
       [line: 3, column: 1]
     code:  Sourceror.get_end_position(quoted) === [line: 3, column: 1]
     left:  [line: 3, column: 3]
     right: [line: 3, column: 1]
     stacktrace:
       lib/sourceror.ex:562: Sourceror (module)