DEPR: correct deprecation message for datetools
Small error in the datetools depr message I just noticed:

Before ("Day.Day"):

```
In [33]: from pandas import datetools

In [34]: datetools.Day(1)
/home/joris/miniconda3/envs/dev/bin/ipython:1: FutureWarning: pandas.core.datetools.Day is deprecated. Please use pandas.tseries.offsets.Day.Day instead.
  #!/home/joris/miniconda3/envs/dev/bin/python
Out[34]: <Day>
```

After:

```
In [2]: datetools.Day(1)
/home/joris/miniconda3/envs/dev/bin/ipython:1: FutureWarning: pandas.core.datetools.Day is deprecated. Please use pandas.tseries.offsets.Day instead.
  #!/home/joris/miniconda3/envs/dev/bin/python
Out[2]: <Day>
```
# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/16202?src=pr&el=h1) Report
> Merging [#16202](https://codecov.io/gh/pandas-dev/pandas/pull/16202?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/20fda2223d5121be3f8204702b5ce1e6037e5b18?src=pr&el=desc) will **decrease** coverage by `<.01%`.
> The diff coverage is `100%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/16202/graphs/tree.svg?src=pr&token=eZ4WkYLtcO&width=650&height=150)](https://codecov.io/gh/pandas-dev/pandas/pull/16202?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #16202      +/-   ##
==========================================
- Coverage   90.86%   90.86%   -0.01%     
==========================================
  Files         162      162              
  Lines       50871    50871              
==========================================
- Hits        46225    46223       -2     
- Misses       4646     4648       +2
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `88.64% <100%> (-0.01%)` | :arrow_down: |
| #single | `40.31% <0%> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/16202?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/util/depr\_module.py](https://codecov.io/gh/pandas-dev/pandas/pull/16202?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvZGVwcl9tb2R1bGUucHk=) | `79.06% <100%> (ø)` | :arrow_up: |
| [pandas/core/common.py](https://codecov.io/gh/pandas-dev/pandas/pull/16202?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvY29tbW9uLnB5) | `90.68% <0%> (-0.35%)` | :arrow_down: |
| [pandas/core/indexes/datetimes.py](https://codecov.io/gh/pandas-dev/pandas/pull/16202?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW5kZXhlcy9kYXRldGltZXMucHk=) | `95.33% <0%> (-0.1%)` | :arrow_down: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/16202?src=pr&el=continue).
> **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta)
> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/16202?src=pr&el=footer). Last update [20fda22...d29e2a2](https://codecov.io/gh/pandas-dev/pandas/pull/16202?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/16202?src=pr&el=h1) Report
> Merging [#16202](https://codecov.io/gh/pandas-dev/pandas/pull/16202?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/20fda2223d5121be3f8204702b5ce1e6037e5b18?src=pr&el=desc) will **decrease** coverage by `<.01%`.
> The diff coverage is `100%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/16202/graphs/tree.svg?token=eZ4WkYLtcO&width=650&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/16202?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #16202      +/-   ##
==========================================
- Coverage   90.86%   90.86%   -0.01%     
==========================================
  Files         162      162              
  Lines       50871    50871              
==========================================
- Hits        46225    46223       -2     
- Misses       4646     4648       +2
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `88.64% <100%> (-0.01%)` | :arrow_down: |
| #single | `40.31% <0%> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/16202?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/util/depr\_module.py](https://codecov.io/gh/pandas-dev/pandas/pull/16202?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvZGVwcl9tb2R1bGUucHk=) | `79.06% <100%> (ø)` | :arrow_up: |
| [pandas/core/common.py](https://codecov.io/gh/pandas-dev/pandas/pull/16202?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvY29tbW9uLnB5) | `90.68% <0%> (-0.35%)` | :arrow_down: |
| [pandas/core/indexes/datetimes.py](https://codecov.io/gh/pandas-dev/pandas/pull/16202?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW5kZXhlcy9kYXRldGltZXMucHk=) | `95.33% <0%> (-0.1%)` | :arrow_down: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/16202?src=pr&el=continue).
> **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta)
> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/16202?src=pr&el=footer). Last update [20fda22...d29e2a2](https://codecov.io/gh/pandas-dev/pandas/pull/16202?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 This looks good.

We can do this elsewhere, but I noticed a couple of others that should be removed / moved in datetools.

- ABCDataFrame
- ABCSeries
- ABCIndexClass
- is_integer
- is_scalar
- notnull
- normalize_date (move?)
- DateParseError (do we need to expose this?)

Moves

- is_timedelta64_dtype (maybe)
- unique : pandas.unique
- Timedelta: pandas.Timedelta that entire module is deprecated I wouldn't change anything else. Yeah, Tom, I think the other ones you listed are normally not used from that module, so in principle we should add more manual redirects, but for those it is not a priority I think.

For the `normalize_date ` there is a `normalize` method on Timestamp/DatetimeIndex as alternative, so not needed to move this I think