BUG: sql_schema does not generate dialect-specific DDL

Release notes update
DOC: v0.15.2 typos
ENH: Timestamp: Support addl datetime classmethods

* `utcfromtimestamp`,`timestamp`, and `combine` now supported
* Closes #5351.
Merge pull request #8827 from artemyk/get_schema_fix_8697

BUG: sql_schema does not generate dialect-specific DDL
Merge pull request #8837 from jtratner/addl-timestamp-classmethods

ENH: Timestamp: Support addl datetime classmethods
DOC GH3508 (bis) added basic documentation of google analytics  in remote_data
BUG: Stacking with multiple mixed int/str levels

Add test case for mixed type stacking

Used wrong var name in the assert

Method to swap levels assuming ints are level numbers

Fix _stack_multi_columns to deal with mixed strs/ints

Extra testcases

Add fix to the release notes

Convert to label before swaplevel if possible

Revert "Method to swap levels assuming ints are level numbers"

This reverts commit 61f96fd3cb23cda9f9c7a6837b145ebd247a55cc.

More test cases

Use _convert_level_number() to sort columns