StataWriter: Replace missing values in string columns by an empty string
BENCH: add vbench for issue 6697
Merge branch 'StataParser' of https://github.com/PKEuS/pandas into PKEuS-StataParser

Conflicts:
	doc/source/release.rst
Merge pull request #6825 from cpcloud/replace-dict-vbenches

BENCH: add vbench for issue 6697
BUG: fix replace bug where different dtypes in a nested dict would only replace the first value