3D ndarray (NxNxN) to DataFrame (NxNxN rows and 4 columns = 3 indices + 1 value)
I have a ndarray (between 4 or 6 dimensions), but let's talk about 3D data.
so if I have an index like:

``` python
data[i,j,k] = 30
```

How can I create a excel sheet where the first 3 colunns are the indices like:

``` python
>>> frame
  i     j     k       X
  0     0     0    1023
...
  0     0   255       3
...
  0     1     0      34
...
255   255   255      23
```

So, if I have a 256x256x256 ndarray cube, I would like 256x256x256 rows, and 4 columns (3 for indices and 1 for value). I tried to use `Panel`, `to_frame` and `to_csv`, but the third dimension are the columns.

Thanks
