Update to Elixir v0.14.0

[josevalim]

We need to upgrade to Elixir v0.14.0-dev:

• v0.14.0 no longer supports module.__info__(:docs). Instead Code.get_docs(module, :all) should be used
• There are no longer records in v0.14.0-dev. We should remove support for records in ExDoc and instead check if the module defines a __struct__ function. If such function is defined and its documentation is not set to false, we are going to tag it as struct. We will also detect exceptions similarly if the struct has an exception field
• We are going to get rid of the Modules | Records | Protocols pages in favor of a single listing. We will still keep the tags so they are shown along side the module name in the module page, but we will no longer break the listing

[ericmj]

Should we keep the list of fields for structs and exceptions that we had for records?

https://github.com/elixir-lang/ex_doc/blob/master/lib/ex_doc/html_formatter/templates/module_template.eex#L65

(I'm working on task 2)

[josevalim]

No I wouldn't do it for now because:

1. You can see it in the type
2. People should explicitly document fields

If it is an issue, we can revisit later.

[ericmj]

Task 2 done. Only thing left to do is to change the HTML/CSS which I will leave to someone who is more capable :).

[josevalim]

Do you mean the HTML/CSS from task 3? Because task 2 has no HTML/CSS. :D

[josevalim]

All done. I have kept the listing as modules / exceptions / protocols because mixing everything was too confusing.