Update (or remove) Hoogle plugin

[alanbriolat]

We use(d) the JSON API of Hoogle version 4 at http://www.haskell.org/hoogle, but this is now a redirect to Hoogle version 5 at https://hoogle.haskell.org/.

Version 5 has changed the layout of the API responses, and also includes HTML markup. Example request/response from version 5:

$ curl -vL 'https://hoogle.haskell.org/?mode=json&hoogle=map&start=1&count=1' | jq 
[
  {
    "url": "https://hackage.haskell.org/package/base/docs/Prelude.html#v:map",
    "module": {
      "url": "https://hackage.haskell.org/package/base/docs/Prelude.html",
      "name": "Prelude"
    },
    "package": {
      "url": "https://hackage.haskell.org/package/base",
      "name": "base"
    },
    "item": "<span class=name><s0>map</s0></span> :: (a -&gt; b) -&gt; [a] -&gt; [b]",
    "type": "",
    "docs": "<a>map</a> <tt>f xs</tt> is the list obtained by applying <tt>f</tt>\nto each element of <tt>xs</tt>, i.e.,\n\n<pre>\nmap f [x1, x2, ..., xn] == [f x1, f x2, ..., f xn]\nmap f [x1, x2, ...] == [f x1, f x2, ...]\n</pre>\n"
  }
]

There are 2 options for resolving this issue:

• Remove the plugin entirely: it's apparently taken months for us to notice this change, which says something about how often the plugin is used
• Update the plugin for the new JSON format, stripping HTML tags and decoding HTML entities, with an appropriate test suite of example API responses and plugin output