* TSX rises 20.09 points, or 0.16 percent, to 12,878.58 * Index hits highest level since August 2011 * Seven of 10 main index sectors decline * Inmet shares up 2 pct after First Quantum extends offer By John Tilak TORONTO, March 12 (Reuters) - Canada's main stock index closed up on Tuesday and hit a 19-month high earlier in the day as gold shares made strong gains on the highest bullion price in nearly two weeks, helping offset worries about the European economy and weakness