header values should always be strings (at least "flup" cares)
updated circleci config (still with some ugly workaround to rewrite to MySQL host on Debian)
added python3-markdown2 package dependency for Ubuntu 20.04 test
updated circleci config to also test on Ubuntu 20.04
fixed string encoding of SSHA encoded passwords in Python 3
fixed logout action when there is no session
call_user_func passes args by value
fix dba _has_links