Rewrite Autolink suite to go exclusively through project_doc

[josevalim]

See discussion here: #896 (comment)

[eksperimental]

I will tackle this. Thank you

[eksperimental]

So what is next? Should we remove the {elixir, erlang}_{function, module}, and locals?

[josevalim]

@eksperimental I have already removed the other functions and I pushed. :)

[eksperimental]

Great. So anything left to do related to these changes?

[josevalim]

I don't think so! <3

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