Registers an extension.
Twig_ExtensionInterface $extension A Twig_ExtensionInterface instance:
public function addExtension(Twig_ExtensionInterface $extension) {
if ($this->extensionInitialized) {
throw new LogicException(sprintf('Unable to register extension "%s" as extensions have already been initialized.', $extension
->getName()));
}
$this->extensions[$extension
->getName()] = $extension;
}