items returned by itertuples do not act like namedtuples.
I don't know if this is a doc bug, a code bug, or an expectation error on my part.  
The documentation of [itertuples](http://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.itertuples.html) says this function will "Iterate over DataFrame rows as namedtuples", but the resulting items are not namedtuple and cannot be indexed by name like a namedtuple.
#### Code Sample, a copy-pastable example if possible

```
import pandas as pd

df = pd.DataFrame({'col1': [1, 2], 'col2': [0.1, 0.2]},
                     index=['a', 'b'])
for row in df.itertuples():
    print(row)
    print(row['col1'])
```

```
$ python pandasbug.py 
Pandas(Index='a', col1=1, col2=0.10000000000000001)
Traceback (most recent call last):
  File "pandasbug.py", line 8, in <module>
    print(row['col1'])
TypeError: tuple indices must be integers, not str
```
#### Expected Output

```
$ python pandasbug.py 
Pandas(Index='a', col1=1, col2=0.10000000000000001)
1
Pandas(Index='b', col1=2, col2=0.20000000000000001)
2
```
#### output of `pd.show_versions()`

```
$ python -c 'import pandas as pd; pd.show_versions()'

INSTALLED VERSIONS
------------------
commit: None
python: 2.7.6.final.0
python-bits: 64
OS: Linux
OS-release: 3.13.0-45-generic
machine: x86_64
processor: x86_64
byteorder: little
LC_ALL: None
LANG: en_US.UTF-8

pandas: 0.18.0
nose: None
pip: 8.1.1
setuptools: 2.2
Cython: None
numpy: 1.11.0
scipy: None
statsmodels: None
xarray: None
IPython: None
sphinx: None
patsy: None
dateutil: 2.5.2
pytz: 2016.3
blosc: None
bottleneck: None
tables: None
numexpr: None
matplotlib: None
openpyxl: None
xlrd: 0.9.4
xlwt: None
xlsxwriter: None
lxml: None
bs4: None
html5lib: None
httplib2: None
apiclient: None
sqlalchemy: 1.0.12
pymysql: None
psycopg2: 2.6.1 (dt dec pq3 ext)
jinja2: None
boto: None
```
