get_filter() now returns a tuple "(allowed, denied)", normalize() handles "None" values now
Implemented inverted filters for "user", "client" and "address" and cleaned up validation
Adjusted logging, fix for possible valid_address() bug
Catch IP address/network parsing errors
Merge branch 'feature/inverted-filters' into release/0.8.4.0
Bumped version to 0.8.4.0
Merge branch 'release/0.8.4.0' into develop