Server/PacketIO: Updated Mail structures and opcodes.
Updated CMSG_GET_MAIL_LIST structure and opcode.
Updated SMSG_MAIL_LIST_RESULT structure and opcode.
Updated CMSG_SEND_MAIL structure and opcode.
Updated SMSG_SEND_MAIL_RESULT structure and opcode.
Updated CMSG_MAIL_CREATE_TEXT_ITEM structure and opcode.
Updated CMSG_MAIL_DELETE structure and opcode.
Updated CMSG_MAIL_MARK_As_READ structure and opcode.
Updated CMSG_MAIL_TAKE_ITEM structure and opcode.
Updated CMSG_MAIL_TAKE_MONEY structure and opcode.