fix two instances being created by the container instead of a single …

…one when replace_default_engine => true

README.md

@@ -53,6 +53,7 @@ $myfilter = new Twig_Filter( 'myfilter', function( $string ) {
     return strtoupper( $string );
 } );
 
+// WPEmerge::resolve() used for brevity's sake - use a Service Provider instead.
 $twig = WPEmerge::resolve( WPEMERGETWIG_VIEW_TWIG_VIEW_ENGINE_KEY );
 $twig->environment()->addFilter( $myfilter );
 ```

src/View/ServiceProvider.php

@@ -33,7 +33,9 @@ public function register( $container ) {
 		};
 
 		if ( $container[ WPEMERGE_CONFIG_KEY ]['twig']['replace_default_engine'] ) {
-			$container[ WPEMERGE_VIEW_ENGINE_KEY ] = $container->raw( WPEMERGETWIG_VIEW_TWIG_VIEW_ENGINE_KEY );
+			$container[ WPEMERGE_VIEW_ENGINE_KEY ] = function( $c ) {
+				return $c[ WPEMERGETWIG_VIEW_TWIG_VIEW_ENGINE_KEY ];
+			};
 		}
 	}