templates: update to include basic ZCI attributes.

There will likely be some debate about whether or not to include the
`is_cached` value, but I like making it explicit even when there is
a default.

On the `answer_type`, the tests as produced by `duckpan new` could
not pass. It might not be entirely clear to the new developer how to
add the `answer_type` and fix them.
DuckDuckGo: respond to question form.

- Allow for ?s
- Skip some question filler words
Merge pull request #639 from mwmiller/new_templates

templates: update to include basic ZCI attributes.
Merge pull request #648 from mwmiller/questionable_ddg

DuckDuckGo: respond to question form.
DuckDuckGo: hidden service updates.

- Play down its status as a "hidden service", since we widely
  adverterize the availability of such.
- Add more 'onion'-y keys.