BUG: DatetimeIndex with time as key
Doc change for Issue #8805
Merge pull request #8912 from vvbchaves/master

DOC: Issue #8805
DOC: specify return type in to_datetime
CLN: move import to top of file

For consistency with [PEP8][1]:

    Imports are always put at the top of the file, just after any module
    comments and docstrings, and before module globals and constants.

[1]: https://www.python.org/dev/peps/pep-0008#id17
Merge pull request #8922 from aevri/refactor/move_import

CLN: move import to top of file
BUG: Option context applies on __enter__

Option context no longer overrides options when used outside a `with`
statement.

Added test TestConfig.test_option_config_scope

Closes #8514
Merge pull request #8921 from jorisvandenbossche/docstring-to_datetime

DOC: specify return type in to_datetime
Merge pull request #8925 from hkleynhans/fix/8514_option_context_with

BUG: Option context applies on __enter__
BUG: fix doctests in pandas.core.common

$ nosetests pandas/core/common.py --with-doc -v
Merge pull request #8907 from behzadnouri/time-slice

BUG: DatetimeIndex with time object as key
Categorical: let unique only return used categories
Merge pull request #8931 from rupertthompson/fix/core_common_doctests

BUG: fix doctests in pandas.core.common
TST: 32-bit construction fix re GH8907
Merge pull request #8937 from JanSchulz/cat_unique2

Categorical: let unique only return used categories
PERF: add exact kw to to_datetime to enable faster regex format parsing for datetimes
fixes