Massive refactor

- Use contextual namespaces within Flarum\Core
- Clean up and docblock everything
- Refactor Activity/Notification blueprint stuff
- Refactor Formatter stuff
- Refactor Search stuff
- Upgrade to JSON-API 1.0
- Removed “addedPosts” and “removedPosts” relationships from discussion
API. This was used for adding/removing event posts after renaming a
discussion etc. Instead we should make an additional request to get all
new posts

Todo:
- Fix Extenders and extensions
- Get rid of repository interfaces
- Fix other bugs I’ve inevitably introduced

src/Core/Users/Search/Gambits/FulltextGambit.php

@@ -0,0 +1,33 @@
+<?php namespace Flarum\Core\Users\Search\Gambits;
+
+use Flarum\Core\Users\UserRepositoryInterface;
+use Flarum\Core\Search\Search;
+use Flarum\Core\Search\GambitInterface;
+
+class FulltextGambit implements GambitInterface
+{
+    /**
+     * @var UserRepositoryInterface
+     */
+    protected $users;
+
+    /**
+     * @param UserRepositoryInterface $users
+     */
+    public function __construct(UserRepositoryInterface $users)
+    {
+        $this->users = $users;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function apply(Search $search, $bit)
+    {
+        $users = $this->users->getIdsForUsername($bit, $search->getActor());
+
+        $search->getQuery()->whereIn('id', $users);
+
+        $search->setDefaultSort(['id' => $users]);
+    }
+}

src/Core/Users/Search/UserSearch.php

@@ -0,0 +1,7 @@
+<?php namespace Flarum\Core\Users\Search;
+
+use Flarum\Core\Search\Search;
+
+class UserSearch extends Search
+{
+}

src/Core/Users/Search/UserSearcher.php

@@ -0,0 +1,76 @@
+<?php namespace Flarum\Core\Users\Search;
+
+use Flarum\Core\Search\AppliesParametersToSearch;
+use Flarum\Core\Search\GambitManager;
+use Flarum\Core\Search\SearchCriteria;
+use Flarum\Core\Search\SearchResults;
+use Flarum\Core\Users\UserRepositoryInterface;
+use Flarum\Core\Users\Events\UserSearchWillBePerformed;
+
+/**
+ * Takes a UserSearchCriteria object, performs a search using gambits,
+ * and spits out a UserSearchResults object.
+ */
+class UserSearcher
+{
+    use AppliesParametersToSearch;
+
+    /**
+     * @var GambitManager
+     */
+    protected $gambits;
+
+    /**
+     * @var UserRepositoryInterface
+     */
+    protected $users;
+
+    /**
+     * @param GambitManager $gambits
+     * @param UserRepositoryInterface $users
+     */
+    public function __construct(GambitManager $gambits, UserRepositoryInterface $users)
+    {
+        $this->gambits = $gambits;
+        $this->users = $users;
+    }
+
+    /**
+     * @param SearchCriteria $criteria
+     * @param int|null $limit
+     * @param int $offset
+     * @param array $load An array of relationships to load on the results.
+     * @return SearchResults
+     */
+    public function search(SearchCriteria $criteria, $limit = null, $offset = 0, array $load = [])
+    {
+        $actor = $criteria->actor;
+
+        $query = $this->users->query()->whereVisibleTo($actor);
+
+        // Construct an object which represents this search for users.
+        // Apply gambits to it, sort, and paging criteria. Also give extensions
+        // an opportunity to modify it.
+        $search = new UserSearch($query->getQuery(), $actor);
+
+        $this->gambits->apply($search, $criteria->query);
+        $this->applySort($search, $criteria->sort);
+        $this->applyOffset($search, $offset);
+        $this->applyLimit($search, $limit + 1);
+
+        event(new UserSearchWillBePerformed($search, $criteria));
+
+        // Execute the search query and retrieve the results. We get one more
+        // results than the user asked for, so that we can say if there are more
+        // results. If there are, we will get rid of that extra result.
+        $users = $query->get();
+
+        if ($areMoreResults = ($limit > 0 && $users->count() > $limit)) {
+            $users->pop();
+        }
+
+        $users->load($load);
+
+        return new SearchResults($users, $areMoreResults);
+    }
+}