IPv6 support

In order to support IPv6 addresses to connect to MySQL, Perl DBD::MySQL driver v4.033_01 is required. Also, as stated in RFC 3986 https://www.ietf.org/rfc/rfc3986.txt section 3.2.2 brackes must be used to distinguish host and port. Examples: https://metacpan.org/pod/DBD::mysql#port