read_csv, compression, and bad column names.
Hi.  I've got a data set that I'm working with from [here](http://epp.eurostat.ec.europa.eu/NavTree_prod/everybody/BulkDownloadListing?dir=data&sort=1&sort=2&start=b), the `bop_its_det.tsv.gz` file.  [Direct Link](http://epp.eurostat.ec.europa.eu/NavTree_prod/everybody/BulkDownloadListing?sort=1&file=data%2Fbop_its_det.tsv.gz). It's about 80 MB unzipped.  I tried to create a csv of just the first 10 rows [here](https://www.dropbox.com/s/u1pz5gvbwwaupjn/test.csv) but I think I messed up some of the newlines.  [Here's](https://gist.github.com/4286107) a gist of the plain text.

I want to say up front that I'm using pandas version `0.10.0.dev-16774b3`, which I think is from a couple days before the official 10.0 beta was released, so maybe this isn't an issue anymore.

Someone in the EU's stats department decided it would be a good idea to separate some column names by columns and others by tabs so the first line looks like

```
In [332]: f = open('BulkDownloadListing.tsv', 'r')

In [333]: f.readline()
Out[333]: 'currency,post,flow,partner,geo\\time\t2011 \t2010 \t2009 \t2008 \t2007 \t2006 \t2005 \t2004 \n'
```

read_csv can handle this fine with:

```
df = pd.read_csv('BulkDownloadListing.tsv', sep=',|s*\t', na_values=[':', ' :', ': '], nrows=10)
```

when I try with the compressed file `BulkDownloadListing.gz`:

```
df = pd.read_csv('BulkDownloadListing.gz', compression='gzip', sep=',|s*\t', na_values=[':', ' :', ': '], nrows=10)
```

I get 

```
---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-337-07c5e7dff532> in <module>()
----> 1 df = pd.read_csv('BulkDownloadListing.gz', compression='gzip', sep=',|s*\t', na_values=[':', ' :', ': '], nrows=10)
/usr/local/Cellar/python/2.7.3/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pandas-0.10.0.dev_16774b3-py2.7-macosx-10.8-x86_64.egg/pandas/io/parsers.pyc in parser_f(filepath_or_buffer, sep, dialect, compression, doublequote, escapechar, quotechar, quoting, skipinitialspace, lineterminator, header, index_col, names, prefix, skiprows, skipfooter, skip_footer, na_values, true_values, false_values, delimiter, converters, dtype, usecols, engine, delim_whitespace, as_recarray, na_filter, compact_ints, use_unsigned, low_memory, buffer_lines, warn_bad_lines, error_bad_lines, keep_default_na, thousands, comment, decimal, parse_dates, keep_date_col, dayfirst, date_parser, memory_map, nrows, iterator, chunksize, verbose, encoding, squeeze)
    392                     buffer_lines=buffer_lines)
    393 
--> 394         return _read(filepath_or_buffer, kwds)
    395 
    396     parser_f.__name__ = name
/usr/local/Cellar/python/2.7.3/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pandas-0.10.0.dev_16774b3-py2.7-macosx-10.8-x86_64.egg/pandas/io/parsers.pyc in _read(filepath_or_buffer, kwds)
    204 
    205     if nrows is not None:
--> 206         return parser.read(nrows)
    207     elif chunksize or iterator:
    208         return parser
/usr/local/Cellar/python/2.7.3/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pandas-0.10.0.dev_16774b3-py2.7-macosx-10.8-x86_64.egg/pandas/io/parsers.pyc in read(self, nrows)
    622             #     self._engine.set_error_bad_lines(False)
    623 
--> 624         ret = self._engine.read(nrows)
    625 
    626         if self.options.get('as_recarray'):
/usr/local/Cellar/python/2.7.3/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pandas-0.10.0.dev_16774b3-py2.7-macosx-10.8-x86_64.egg/pandas/io/parsers.pyc in read(self, rows)
   1238             content = content[1:]
   1239 
-> 1240         alldata = self._rows_to_cols(content)
   1241         data = self._exclude_implicit_index(alldata)
   1242 
/usr/local/Cellar/python/2.7.3/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pandas-0.10.0.dev_16774b3-py2.7-macosx-10.8-x86_64.egg/pandas/io/parsers.pyc in _rows_to_cols(self, content)
   1454             msg = ('Expected %d fields in line %d, saw %d' %
   1455                    (col_len, row_num + 1, zip_len))
-> 1456             raise ValueError(msg)
   1457 
   1458         return zipped_content
ValueError: Expected 5 fields in line 3, saw 11
```
