remove double negative in objective equation

src/osemosys_fast.txt

@@ -341,7 +341,7 @@ minimize cost: sum{r in REGION, t in TECHNOLOGY, y in YEAR}
             CapitalCost[r,t,y] * NewCapacity[r,t,y] * CapitalRecoveryFactor[r,t] * PvAnnuity[r,t] / DiscountFactor[r,y] + 
             DiscountedTechnologyEmissionsPenalty[r,t,y] - DiscountedSalvageValue[r,t,y]) + 
             sum{r in REGION, s in STORAGE, y in YEAR} (CapitalCostStorage[r,s,y] * NewStorageCapacity[r,s,y] / DiscountFactorStorage[r,s,y] - 
-            - SalvageValueStorage[r,s,y] / ((1+DiscountRateStorage[r,s])^(max{yy in YEAR} max(yy)-min{yy in YEAR} min(yy)+1)));
+            SalvageValueStorage[r,s,y] / ((1+DiscountRateStorage[r,s])^(max{yy in YEAR} max(yy)-min{yy in YEAR} min(yy)+1)));
 
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