ENH: Restore original convert_objects and add _convert
Restores the v0.16 behavior of convert_objects and moves the new
version of _convert
Adds to_numeric for directly converting numeric data

closes #11116
closes #11133

Still a few things to do:
-  [x] Update release notes to remove new docs and add deprecation note
-  [x] Make sure `copy` is passed to `_possibly_convert_objects`
-  [x] Add note about bugs fixed in `convert_objects`
-  [x] Restore docs for `convert_objects`
-  [x] Add tests for `to_numeric`
-  [ ] Add docs for `to_numeric`
-  [x] Move converters to a new file, `convert.py`
 The important changes are:

`convert` in `ObjectManager`: https://github.com/pydata/pandas/pull/11173/files#diff-e705e723b2d6e7c0e2a0443f80916abfR1521

This change requires this to 'route' to either the old or new style converter. 

`to_numeric`: https://github.com/pydata/pandas/pull/11173/files#diff-40d1f19921aa9f2932951124fad07cc6R53

New function.
 @bashtage Really thanks a lot for this! 

(I am still not fully convinced the deprecation is needed, but I will try to summarize my reasons tomorrow)
 @bashtage 
- pls move the 2 converting functions either to a new module, `core/convert.py`. 
- let's finish up the documentation changes.

pls let me know asap.
 Still no tests for `to_numeric` or docs for this method.
 looks good! ping when tests for `pd.to_numeric`
 @jorisvandenbossche ok with this
 `to_numeric` needs some fixes (and tests): `lib` is not yet imported, `lib.maybe_convert_numeric` expects an array so it bugs on a series as arg, and the final result needs to be boxed into a series again if the arg was a series.
 Yes - it definitely needs work.  It expects something with the buffer
interface, so I need to ensure that this works as expected.

On Sun, Sep 27, 2015 at 8:12 PM Joris Van den Bossche <
notifications@github.com> wrote:

> to_numeric needs some fixes (and tests): lib is not yet imported,
> lib.maybe_convert_numeric expects an array so it bugs on a series as arg,
> and the final result needs to be boxed into a series again if the arg was a
> series.
> 
> —
> Reply to this email directly or view it on GitHub
> https://github.com/pydata/pandas/pull/11173#issuecomment-143606211.
 @bashtage did you have a chance to add some tests here?
 Should be ready when green I think
 Can squash commits - wanted to make it easier to see changes at each stage since close to release
 @jreback Green - let me know if I missed anything.  Only tick left is to add some docs although this can probably wait since `convert_objects` is still available.
 All addressed
 @jreback It is green - or should be since all required tests passed.
 @bashtage thanks for all of the work on this!
