PEP: pandas/core round 7 (window, reshape, series, format)

And residual categorical.    What should we do with api/sparse/matrix
as those are all unused imports--noqa for each line?

Author: rockg <grant.roch@gmail.com>

Closes #12099 from rockg/pep8-round7 and squashes the following commits:

2e61f9c [rockg] PEP: pandas/core round 7 (window, reshape, series, format, minor categorical)

Author: rockg

pandas/core/categorical.py

@@ -14,11 +14,11 @@
 from pandas.util.decorators import cache_readonly, deprecate_kwarg
 
 from pandas.core.common import (
-    ABCSeries, ABCIndexClass, ABCPeriodIndex, ABCCategoricalIndex, isnull,
-    notnull, is_dtype_equal, is_categorical_dtype, is_integer_dtype,
-    is_object_dtype, _possibly_infer_to_datetimelike, get_dtype_kinds,
-    is_list_like, is_sequence, is_null_slice, is_bool, _ensure_platform_int,
-    _ensure_object, _ensure_int64, _coerce_indexer_dtype, take_1d)
+    ABCSeries, ABCIndexClass, ABCCategoricalIndex, isnull, notnull,
+    is_dtype_equal, is_categorical_dtype, is_integer_dtype,
+    _possibly_infer_to_datetimelike, get_dtype_kinds, is_list_like,
+    is_sequence, is_null_slice, is_bool, _ensure_object, _ensure_int64,
+    _coerce_indexer_dtype, take_1d)
 from pandas.core.dtypes import CategoricalDtype
 from pandas.util.terminal import get_terminal_size
 from pandas.core.config import get_option