Implement an Option that annotates the AST with the parsed verbatim text (HTML tags only?)

[RobertDober]

This was discussed in pragdave/earmark#356 as follows
Do you mean

   {"div", [{"class", "elixir"}] [best code ever] %{verbatim: true}}

--->

   {"div", [{"class", "elixir"}] [best code ever] %{verbatim: true, html: ~s[<div class="elixir">best code ever</div>]}}

sure sounds like a sound idea to me.

Remains to be seen if the Option shall be capable of adding the verbatim content for other elements too, which might give

e.g.

     as_ast("<div....</div>**hello**", include_verabtims_for: :all) # :verbatim, :none (default) ?

   {:ok,
          [
               {"div", [{"class", "elixir"}] [best code ever] %{verbatim: true, verbatim_content: ~s[<div class="elixir">best code ever</div>]}
},           {"p", [], [{"strong", [], "hello", %{verbatim_content: "**hello**"}], %{verbatim_content: "**hello**"}], []

--->

[RobertDober]

Merging this into #7