Improvements to document outline

[lukaszsamson]

This PR introduces many improvements and fixes to document outline provider.

• Includes support for nested modules and ExUnit describe blocks (basing on https://github.com/kent-medin/elixir-ls/commit/14c892b4e96015345a537f68312abe1b92e1981e) which fixes Incorporate nested outline view #67 (and originally Add nested outline view JakeBecker/elixir-ls#188 and Outline doesn't seem to support describe blocks in test files JakeBecker/elixir-ls#178)
• Adds support for ExUnit setup and setup_all blocks
• Adds support for atoms in module names (fixes Using regular atoms as module names kills outline query JakeBecker/elixir-ls#187)
• Adds support for protocols and implementations
• Adds support for types and callbacks
• Adds support for structs and exceptions
• Adds support for guards, delegates and private macros
• Adds support for elixir config files

[lukaszsamson]

It looks like code in this PR triggered an inconsistency in elixir formatter as it reports not formatted on < 1.9

[axelson]

Hmmm, the diff is annoying:

-        [{:"::", _, [{_, _, _} = type_head | _]}] ->
+        [{:::, _, [{_, _, _} = type_head | _]}] ->
           Macro.to_string(type_head)

-        [{:when, _, [{:"::", _, [{_, _, _} = type_head, _]}, _]}] ->
+        [{:when, _, [{:::, _, [{_, _, _} = type_head, _]}, _]}] ->

One workaround is to use a binding. So something like:

type_separator = String.to_atom("::")
case type_expression do
  [{^type_separator, _, [{_, _, _} = type_head | _]}] ->
  ...

That's perhaps a little uglier, but at least it is straightforward and semantically the same. Alternatively we could try to run the formatter check only 1.9.x, but I'm not sure how to do that with travis.

[NobbZ]

Alternatively we could try to run the formatter check only 1.9.x, but I'm not sure how to do that with travis.

As far as I know, there is ELIXIR_VERSION environment variable set up by travis.

Therefore doing something like this should work:

script:
  - MIX_ENV=test mix compile --force --warnings-as-errors
  - [[ ${ELIXIR_VERSION} == 1.9* ]] && mix format --check-formatted
  - mix test

[lukaszsamson]

@axelson I managed to enable conditional check.
@NobbZ your suggestion would not work properly as it would return non 0 exit code if ${ELIXIR_VERSION} == 1.9* condition were not satisfied causing the build to fail. Besides, the env in question is TRAVIS_ELIXIR_VERSION

[axelson]

Looks good!