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* [sec ] fix XSS injection in the url redirect in the login page (thanks to jthiltges)
* [fix ] fix configuration consistency check for attribute file (error if a given backend is not declared in main .ini file but in attributes)
* [fix ] remove a few deprecation warnings
* [fix ] fix potential issue with group names containing non-ascii characters
* [feat] support for python 3
* [feat] support for python-ldap 3.X.X
* [impr] better log error message if inconsistency between role, attribute and main .ini file for backends
* [impr] more systematic use of html and url escaping in the html rendering to prevent against content injection (thanks to jthiltges)
* [impr] more testing for various versions of python and python-ldap