[Bf-python] NMesh module and vertex groups

[models at paposo.com]

> > About the new vgrouping methods: sure, those are necessary additions.
> > That's your area ; ), will you implement them, Joseph?

How about this: (for checking :)
I noticed that vgroup names must be no longer than 32 chars so I also add
this check to addVertGroup()

static PyObject *NMesh_renameVertGroup (PyObject *self, PyObject *args)
{
 char * oldGr;
 char * newGr;
 bDeformGroup * defGroup;

 if (!PyArg_ParseTuple(args, "ss", &oldGr, &newGr))
  return EXPP_ReturnPyObjError (PyExc_TypeError,
   "Expected string & string argument");

 defGroup = NULL;

 if(!((BPy_NMesh*)self)->object)
  return EXPP_ReturnPyObjError (PyExc_RuntimeError,
   "This mesh must be linked to an object");

 if (strlen(newGr) > 32 || strlen(newGr) < 1)
  return EXPP_ReturnPyObjError (PyExc_RuntimeError,
   "Group names must be between 1 and 32 characters");

 defGroup = get_named_vertexgroup(((BPy_NMesh*)self)->object, oldGr);
 if(defGroup == NULL)
  return EXPP_ReturnPyObjError (PyExc_RuntimeError,
   "Couldn't find the expected vertex group");

 strcpy (defGroup->name, newGr);
 unique_vertexgroup_name(defGroup, ((BPy_NMesh*)self)->object);

 return EXPP_incr_ret (Py_None);
}

static PyObject *NMesh_getVertGroupNames (PyObject *self, PyObject *args)
{
 bDeformGroup * defGroup;
 PyObject *list;

 if(!((BPy_NMesh*)self)->object)
  return EXPP_ReturnPyObjError (PyExc_RuntimeError,
   "This mesh must be linked to an object");

 list = PyList_New(0);
 for (defGroup = (((BPy_NMesh*)self)->object)->defbase.first; defGroup;
defGroup=defGroup->next){
  if(PyList_Append(list,PyString_FromString(defGroup->name)) < 0)
   return EXPP_ReturnPyObjError (PyExc_RuntimeError,
    "Couldn't add item to list");
 }

 return list;
}