message: Update comment for L2ProjectionGridTransfer
  Describe limitation of this operator when applied to H1 finite element spaces.
diff: @@ -734,11 +734,18 @@ public:
  defined in physical space and, generally, vary between different mesh
  elements.
  - This class currently supports only L2 finite element spaces and fine meshes
  - that are a uniform refinement of the coarse mesh. Generally, the coarse and
  - fine FE spaces can have different orders, however, in order for the backward
  - operator to be well-defined, the number of the fine dofs (in a coarse
  - element) should not be smaller than the number of coarse dofs. */
  + This class currently only fully supports L2 finite element spaces and fine
  + meshes that are a uniform refinement of the coarse mesh. Generally, the
  + coarse and fine FE spaces can have different orders, however, in order for
  + the backward operator to be well-defined, the number of the fine dofs (in a
  + coarse element) should not be smaller than the number of coarse dofs.
  +
  + If used on H1 finite element spaces, the transfer will be performed locally,
  + and the value of shared (interface) degrees of freedom will be determined by
  + the value of the last transfer to be performed (according to the element
  + numbering in the finite element space). As a consequence, the mass
  + conservation properties for this operator from the L2 case do not carry over
  + to H1 spaces. */
  class L2ProjectionGridTransfer : public GridTransfer
  {
  protected:
  