DOC: Remove quasi-non-public parts of Index API from API docs

[jtratner]

We added some notes on Index to the API Reference that probably
shouldn't be there at all, since they're not meant for public
consumption or not documented. I've slimmed down the methods to set
ops, copy, metadata (i.e. names) and a few of the DatetimeIndex methods.

[jtratner]

@jorisvandenbossche look okay to you? Anything you think ought to be there?

[jreback]

I think h ought to leave the datetime selectors, eg day,hour,etc

also tolist

[rockg]

I would really prefer these to stay. Many times I have had to go to the index objects themselves to perform operations. These methods should be documented for somebody who requires more control over the index objects. The disclaimer at the beginning of the index section alludes to the fact that many of the index operations should be done at the dataframe and series level and I would really prefer to keep it that way. It will save people a lot of time looking for documentation rather than going to the source code. To make it more concrete we could put an asterix by the private methods. Please keep this around.

[jorisvandenbossche]

The datetime components should indeed certainly stay I think. For the other methods I have a less strong opinion as I don't use them myself. But methods to select values in the index, like isin seems certainly useful for users to me. @jtratner Can you explain why you think index methods should in general not be public?

And by the way, removing them from the api.rst pages won't remove the docs itself, as they are all linked to at the Index docstring page (http://pandas.pydata.org/pandas-docs/dev/generated/pandas.Index.html#pandas.Index)

[rockg]

Just for clarification, I found the lack of DatetimeIndex documentation frustrating and that's why I put it in. Personally, I find that DatetimeIndex is used by itself much more than Index as Index has standard replacements such as range, xrange but DatetimeIndex does not and that's why functions like date_range and the DatetimeIndex class are so important. And since DatetimeIndex subclasses Index it made sense to separate those parts of the API. Having the class specific documentation that @jorisvandenbossche points to is great. I still think some of the methods that are removed should remain (all the DatetimeIndex stuff, Index->Selecting section, tolist, order, argsort).

[jreback]

@jorisvandenbossche IIRC you arlready fixed much of this? close this one?

[jreback]

@jtratner closing this.....api been changed quite a bit....pls reopen if needed