Added a trim filter

Closes #634

CHANGELOG

@@ -1,3 +1,7 @@
+* 1.7.0 (2012-XX-XX)
+
+ * added a trim filter
+
 * 1.6.1 (2012-02-29)
 
  * fixed Twig C extension

lib/Twig/Extension/Core.php

@@ -137,6 +137,7 @@ class Twig_Extension_Core extends Twig_Extension
             'upper'      => new Twig_Filter_Function('strtoupper'),
             'lower'      => new Twig_Filter_Function('strtolower'),
             'striptags'  => new Twig_Filter_Function('strip_tags'),
+            'trim'       => new Twig_Filter_Function('trim'),
             'nl2br'      => new Twig_Filter_Function('nl2br', array('pre_escape' => 'html', 'is_safe' => array('html'))),
 
             // array helpers

test/Twig/Tests/Fixtures/filters/trim.test

@@ -0,0 +1,12 @@
+--TEST--
+"trim" filter
+--TEMPLATE--
+{{ "  I like Twig.  "|trim }}
+{{ text|trim }}
+{{ "  foo/"|trim("/") }}
+--DATA--
+return array('text' => "  If you have some <strong>HTML</strong> it will be escaped.  ")
+--EXPECT--
+I like Twig.
+If you have some &lt;strong&gt;HTML&lt;/strong&gt; it will be escaped.
+  foo