Deprecated pandas.lib redirect messages
Currently, you get the following message when you try to access one of the `pandas.lib` functions:

```
In [1]: pd.lib.Timedelta
/home/joris/miniconda3/envs/dev/bin/ipython:1: FutureWarning: pandas.lib.Timedelta is deprecated. 
Please use pandas._libs.lib.Timedelta instead.
  #!/home/joris/miniconda3/envs/dev/bin/python
Out[1]: pandas._libs.tslib.Timedelta

In [1]: pd.lib.is_bool
/home/joris/miniconda3/envs/dev/bin/ipython:1: FutureWarning: pandas.lib.is_bool is deprecated. 
Please use pandas._libs.lib.is_bool instead.
  #!/home/joris/miniconda3/envs/dev/bin/python
Out[1]: <function pandas._libs.lib.is_bool>
```

(apart from `infer_dtypes`, for which there is already another redirect).

We shouldn't recommend to use `pandas._lib.lib`. 
For some there is a public alternative (like `Timestamp`, `Timedelta`), others are probably just private and shouldn't have an alternative. 

We could list all of them as `removals` and `moved` in `lib = _DeprecatedModule(..)`, but that will be a long list. Or we could just don't provide an alternative import path by default, and only include some specific ones for which there is an alternative.