Proper configuration settings for modern mysql/mariadb

We do want to use_unicode and we want a utf8mb4 charset.

This will allow all unicode planes.
Ensure test database is recreated with proper collation

Otherwise a tiddler named 'One Two' is the same as 'one two',
which we do not want.

Also update setup.py to reflect our plan to use modern python.
Merge branch 'master' into server3