Bug fix for TiTv calculation -- shouldn't be rounding

public/java/src/org/broadinstitute/sting/gatk/walkers/varianteval/evaluators/VariantSummary.java

@@ -131,7 +131,7 @@ public class VariantSummary extends VariantEvaluator implements StandardEval {
                     n++;
                 }
             }
-            return Math.round(sum / (1.0 * n));
+            return sum / (1.0 * n);
         }
     }