Simplify setup of the transfer operators

The setup was needlessly complicated.  I think that's because
it predates the time where std::shared_ptr could be used.

dune/elasticity/common/trustregionsolver.cc

@@ -293,6 +293,8 @@ setup(const typename BasisType::GridView::Grid& grid,
     std::vector<std::shared_ptr<TruncatedCompressedMGTransfer<CorrectionType>>> transferOperators(isP1Basis ? numLevels-1 : numLevels);
 
     // Here we set up the restriction of the leaf grid space into the leaf grid P1/Q1 space
+    // TODO: IIRC that move to P1Basis was only implemented because I didn't have general
+    // prolongation operators between arbitratry FE spaces.
     if (not isP1Basis)
     {
       TransferOperatorType pkToP1TransferMatrix;
@@ -325,13 +327,8 @@ setup(const typename BasisType::GridView::Grid& grid,
     for (int i=0; i<numLevels-1; i++) {
 
         // Construct the local multigrid transfer matrix
-        TruncatedCompressedMGTransfer<CorrectionType>* newTransferOp = new TruncatedCompressedMGTransfer<CorrectionType>;
-        newTransferOp->setup(*grid_,i,i+1);
-
-        auto op = std::make_shared<TruncatedCompressedMGTransfer<CorrectionType>>();
-        transferOperators[i] = op;
-        std::shared_ptr<TransferOperatorType> transferOperatorMatrix = std::make_shared<TransferOperatorType>(newTransferOp->getMatrix());
-        op->setMatrix(transferOperatorMatrix);
+        transferOperators[i] = std::make_shared<TruncatedCompressedMGTransfer<CorrectionType> >();
+        transferOperators[i]->setup(*grid_,i,i+1);
     }
 
     mmgStep->setTransferOperators(transferOperators);