Cache application.encoding within HTML class to avoid unnecessary calls to Config::get();

Calling the "Config::get('application.encoding')" is expensive and within a large form (using the form builder) having it requested multiple times can result in a significant performance drag.

Caching this value reduced calls to Config:get within our project from 1200+ to 125. All core tests appear to pass with this change in place.

laravel/html.php

@@ -9,6 +9,13 @@ class HTML {
 	 */
 	public static $macros = array();
 
+	/**
+	 * Cache application encoding locally to save expensive calls to config::get().
+	 *
+	 * @var string
+	 */
+	public static $encoding = null;
+
 	/**
 	 * Registers a custom macro.
 	 *
@@ -31,7 +38,8 @@ class HTML {
 	 */
 	public static function entities($value)
 	{
-		return htmlentities($value, ENT_QUOTES, Config::get('application.encoding'), false);
+		if(static::$encoding===null) static::$encoding = Config::get('application.encoding');
+		return htmlentities($value, ENT_QUOTES, static::$encoding, false);
 	}
 
 	/**
@@ -42,7 +50,8 @@ class HTML {
 	 */
 	public static function decode($value)
 	{
-		return html_entity_decode($value, ENT_QUOTES, Config::get('application.encoding'));
+		if(static::$encoding===null) static::$encoding = Config::get('application.encoding');
+		return html_entity_decode($value, ENT_QUOTES, static::$encoding);
 	}
 
 	/**
@@ -55,7 +64,8 @@ class HTML {
 	 */
 	public static function specialchars($value)
 	{
-		return htmlspecialchars($value, ENT_QUOTES, Config::get('application.encoding'), false);
+		if(static::$encoding===null) static::$encoding = Config::get('application.encoding');
+		return htmlspecialchars($value, ENT_QUOTES, static::$encoding, false);
 	}
 
 	/**