Fix pattern just like in MorphBlendMesh

src/objects/MorphAnimMesh.js

@@ -57,7 +57,7 @@ THREE.MorphAnimMesh.prototype.parseAnimations = function () {
 
 	var firstAnimation, animations = geometry.animations;
 
-	var pattern = /([a-z]+)(\d+)/;
+	var pattern = /([a-z]+)_?(\d+)/;
 
 	for ( var i = 0, il = geometry.morphTargets.length; i < il; i ++ ) {