Frontend refactor (#1471)

Refactor Frontend + Asset code

- Use Laravel's Filesystem component for asset IO, meaning theoretically
  assets should be storable on S3 etc.

- More reliable checking for asset recompilation when debug mode is on,
  so you don't have to constantly delete the compiled assets to force
  a recompile. Should also fix issues with locale JS files being
  recompiled with the same name and cached.

- Remove JavaScript minification, because it will be done by Webpack
  (exception is for the TextFormatter JS).

- Add support for JS sourcemaps.

- Separate frontend view and assets completely. This is an important
  distinction because frontend assets are compiled independent of a
  request, whereas putting together a view depends on a request.

- Bind frontend view/asset factory instances to the container (in
  service providers) rather than subclassing. Asset and content
  populators can be added to these factories – these are simply objects
  that populate the asset compilers or the view with information.

- Add RouteHandlerFactory functions that make it easy to hook up a
  frontend controller with a frontend instance ± some content.

- Remove the need for "nojs"

- Fix cache:clear command

- Recompile assets when settings/enabled extensions change

src/Settings/Event/Saved.php

@@ -14,26 +14,15 @@ namespace Flarum\Settings\Event;
 class Saved
 {
     /**
-     * The setting key that was set.
-     *
-     * @var string
+     * @var array
      */
-    public $key;
+    public $settings;
 
     /**
-     * The setting value that was set.
-     *
-     * @var string
+     * @param array $settings
      */
-    public $value;
-
-    /**
-     * @param string $key The setting key that was set.
-     * @param string $value The setting value that was set.
-     */
-    public function __construct($key, $value)
+    public function __construct(array $settings)
     {
-        $this->key = $key;
-        $this->value = $value;
+        $this->settings = $settings;
     }
 }

src/Settings/Event/Saving.php

@@ -0,0 +1,28 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * (c) Toby Zerner <toby.zerner@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Flarum\Settings\Event;
+
+class Saving
+{
+    /**
+     * @var array
+     */
+    public $settings;
+
+    /**
+     * @param array $settings
+     */
+    public function __construct(array &$settings)
+    {
+        $this->settings = &$settings;
+    }
+}

src/Settings/OverrideSettingsRepository.php

@@ -0,0 +1,61 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * (c) Toby Zerner <toby.zerner@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Flarum\Settings;
+
+/**
+ * A settings repository decorator that allows overriding certain values.
+ *
+ * The `OverrideSettingsRepository` class decorates another
+ * `SettingsRepositoryInterface` instance but allows certain settings to be
+ * overridden with predefined values. It does not affect writing methods.
+ *
+ * Within Flarum, this can be used to test out new setting values in a system
+ * before they are committed to the database.
+ *
+ * @see \Flarum\Forum\RecompileFrontendAssets For an example usage.
+ */
+class OverrideSettingsRepository implements SettingsRepositoryInterface
+{
+    protected $inner;
+
+    protected $overrides = [];
+
+    public function __construct(SettingsRepositoryInterface $inner, array $overrides)
+    {
+        $this->inner = $inner;
+        $this->overrides = $overrides;
+    }
+
+    public function all()
+    {
+        return array_merge($this->inner->all(), $this->overrides);
+    }
+
+    public function get($key, $default = null)
+    {
+        if (array_key_exists($key, $this->overrides)) {
+            return $this->overrides[$key];
+        }
+
+        return array_get($this->all(), $key, $default);
+    }
+
+    public function set($key, $value)
+    {
+        $this->inner->set($key, $value);
+    }
+
+    public function delete($key)
+    {
+        $this->inner->delete($key);
+    }
+}