StataWriter: Replace non-isalnum characters in variable names by _ inste...
...ad of integral represantation of replaced character. Eliminate duplicates created by replacement.

this looks fine, can you add a release notes entry? 
 Done.
 I had to revert this commit

https://github.com/pydata/pandas/commit/a5a2c9210b9399d84df69826c089095b3920f190

This fails on win32 with python2.6, because of the unicode in the source file

you can do something like this (but then the test breaks)

https://github.com/pydata/pandas/tree/stata_fix

pls submit a new PR with the fixed version
