StataWriter: Replace non-isalnum characters in variable names by _ instead of integral represantation of replaced character. Eliminate duplicates created by replacement.
Merge pull request #5525 from PKEuS/master

StataWriter: Replace non-isalnum characters in variable names by _ inste...
BUG: mixed column selection with dups is buggy (GH5639)
Merge pull request #5640 from jreback/dups_bool

BUG: mixed column selection with dups is buggy (GH5639)
Revert "StataWriter: Replace non-isalnum characters in variable names by _ instead of integral represantation of replaced character. Eliminate duplicates created by replacement."

Fails under py2.6 / win32 because of unicode issues

This reverts commit c57363072acec8138381d033b9b7cb7fcfc575a9.