Fixing a bug that occured when the model was invalid and had no faces (only a line for example).

Such model will not be visible.

git-svn-id: https://jmonkeyengine.googlecode.com/svn/trunk@8468 75d07b2b-3a1a-0410-a2c5-0572b91ccdca

engine/src/blender/com/jme3/scene/plugins/blender/meshes/MeshHelper.java

@@ -128,6 +128,8 @@ public class MeshHelper extends AbstractBlenderHelper {
             if (mFaces == null || mFaces.size() == 0) {
                 return new ArrayList<Geometry>(0);
             }
+        } else{
+        	mFaces = new ArrayList<Structure>(0);
         }
 
         Pointer pMTFace = (Pointer) structure.getFieldValue("mtface");