bugfix: allow "newmtl" directive; handle missing texture/normal indices

wfobj.py

@@ -29,7 +29,7 @@ class WFObj(object):
 
         def add_face(*vrefs):
             def split_vref(vref):
-                parts = map(int, vref.split('/'))
+                parts = map(lambda x: 0 if x == '' else int(x), vref.split('/'))
                 while len(parts) < 3:
                     parts.append(0)
                 return parts
@@ -133,6 +133,7 @@ class WFObj(object):
                 material = self.Material()
                 material_name = parts[1]
                 self.materials[material_name] = material
+                continue
             else:
                 if material is None:
                     raise ValueError('Material directive preceeding "newmtl" on line %d' % lineno)