Sopel-search

* Handle common errors with some amount of grace ([4][])
* Refresh the DDGS client periodically to reduce errors ([5][])

[4]: https://github.com/sopel-irc/sopel-search/pull/4
[5]: https://github.com/sopel-irc/sopel-search/pull/5

Bump DuckDuckGo library minimum version; older releases stopped working.

First release of `sopel-search`.

This new search plugin apes a lot of behaviors from Sopel's built-in `search`,
with the following notable changes:

* `.bing` is no longer available
* `.search` is an alias to `.ddg`, as `.g` was already
* Search `region` and `safesearch` level are now configurable
* `.suggest` uses DuckDuckGo; Google suggestions are still available via the
new `.gsuggest` command (if optional extra dependencies are installed)