* Stocks traded in positive territory for the entire session on Thursday, but just so, closing with a slight gain to extend this week's low volatility. VNM (+2.1%) led gainers as the dairy giant is now up 4.6% over the last three days after bouncing off a five-month low. The index was also helped higher by a group of banks - STB (+3.3%), EIB (+1.1%) and MBB (+0.8%) - which had fallen sharply off their 52-week high before posting gains so far this month. Meanwhile, food processer VCF (+4.7%) matc