show pass number in progress

I find this handy when doing multiple passes. Does not seem to break any tests. Sample output:

```
average    since         example     example  current  current  current  current
loss       last          counter      weight    label  predict features     pass
0.000000   0.000000            3         3.0   0.0000   0.0000        4        0
0.333333   0.666667            6         6.0   0.0000   1.0000        4        0
0.454545   0.600000           11        11.0   0.0000   0.0000        4        0
0.363636   0.272727           22        22.0   1.0000   1.0000        4        0
0.403077   0.442517           44        44.0   1.0000   0.0000        4        0
0.466972   0.532353           87        87.0   0.0000   0.0000        4        0
0.446985   0.426999          174       174.0   1.0000   1.0000        4        0
0.471863   0.496740          348       348.0   0.0000   1.0000        4        0
0.429515   0.387167          696       696.0   0.0000   0.3189        4        0
0.353886   0.278257         1392      1392.0   0.0000   0.0000        4        1
0.204298   0.054711         2784      2784.0   0.0000   0.0000        4        2
0.105472   0.006646         5568      5568.0   1.0000   1.0000        4        5
0.053639   0.001796        11135     11135.0   1.0000   1.0000        4       11
```