Closing all databases in AntoxDB

I hope I fixed #243 (if it wasn't already fixed by the commits below). I had some errors in log regarding databased being blocked. (most probably because it wasn't closed from somewhere else)

After that, I came across another problem: when adding a friend he will became duplicated.
I came with a solution, but @Astonex came with a much shorter and efficient one by commits
e20fca90c8e0ce463575e17603100edf81b0eb
fcc6caf407feb250fbaaec2bff63d96c40a28280