message: Lumbermills yield +1 commerce next to rivers
diff: <iYieldChange>0</iYieldChange>
  <iYieldChange>1</iYieldChange>
  </YieldChanges>
  + <RiverSideYieldChange>
  + <iYield>0</iYield>
  + <iYield>0</iYield>
  + <iYield>1</iYield>
  + </RiverSideYieldChange>
  <bActsAsCity>0</bActsAsCity>
  <bHillsMakesValid>0</bHillsMakesValid>
  <bFreshWaterMakesValid>0</bFreshWaterMakesValid>
  