Feature: Incorporate site search into masthead (#1383)

* Integrate search into masthead
* Fix cutoff descenders in archive article titles
* Remove search page from `/test` site
* Enable masthead search
* Remove dedicated search page
* Fix masthead search form padding
* Improve insertion of search content
* Speed up page transition
* Add fade transition to search content
* Rename visibility class names
* Add `site.search` to _config.yml
* Document site search feature
* Update CHANGELOG and history

docs/_docs/18-history.md

@@ -4,7 +4,7 @@ permalink: /docs/history/
 excerpt: "Change log of enhancements and bug fixes made to the theme."
 sidebar:
   nav: docs
-last_modified_at: 2017-12-04T14:49:13-05:00
+last_modified_at: 2017-12-07T08:52:23-05:00
 toc: true
 ---
 
@@ -18,6 +18,7 @@ toc: true
 * Disable comments in `development` environment. [#1363](https://github.com/mmistakes/minimal-mistakes/pull/1363)
 * Exclude specific pages/posts from search index by adding `search: false` to the YAML Front Matter. [#1369](https://github.com/mmistakes/minimal-mistakes/pull/1369)
 * Add optional `description` key to masthead links for clarifying their purpose with the `title` attribute. [#1380](https://github.com/mmistakes/minimal-mistakes/pull/1380)
+* Incorporate site search into masthead. [#1383](https://github.com/mmistakes/minimal-mistakes/pull/1383)
 
 ### Bug Fixes