Fix some bugs in the Transposer's transferFluid method

* Convert the source tank index from 1-based to 0-based when parsing the
  argument
* Use `count` as an upper limit for the amount to transfer

Author: yut23

src/main/scala/li/cil/oc/server/component/traits/InventoryTransfer.scala

@@ -48,7 +48,7 @@ trait InventoryTransfer extends traits.WorldAware with traits.SideRestricted {
     val sinkSide = checkSideForAction(args, 1)
     val sinkPos = position.offset(sinkSide)
     val count = args.optFluidCount(2)
-    val sourceTank = args.optInteger(3, -1)
+    val sourceTank = args.optInteger(3, -1) - 1
 
     onTransferContents() match {
       case Some(reason) =>

src/main/scala/li/cil/oc/util/FluidUtils.scala

@@ -63,7 +63,7 @@ object FluidUtils {
         stackToDrain = tankProperties(sourceTank).getContents
         if (stackToDrain != null) {
           stackToDrain = stackToDrain.copy()
-          stackToDrain.amount = math.max(stackToDrain.amount, limit)
+          stackToDrain.amount = math.min(stackToDrain.amount, limit)
         }
       }
     }