Merge pull request #3296 from masterleinad/mass_matrix_bf

Add MatrixFreeOperators::MassOperator

diff --cc doc/news/changes.h
index 7edcfd2daae27bb60a6ad2402ff67664b522c546,4d4a07a74a897649966468d63e366fcf38056726..880e669538d1799ef24c099dbda3d552f8641c7d
--- 1/doc/news/changes.h
--- 2/doc/news/changes.h
+++ b/doc/news/changes.h
@@@ -391,19 -391,11 +391,23 @@@ inconvenience this causes
  <h3>Specific improvements</h3>
  
  <ol>
+  <li> New: Add MatrixFreeOperators::MassOperator representing a mass matrix.
+  <br>
+  (Daniel Arndt, 2016/10/27)
+  <li>
  
 + <li> New: Add ArpackSolver::set_shift() to set the shift value in spectral
 + transformation.
 + <br>
 + (Denis Davydov, 2016/10/25)
 + </li>
 +
 + <li> New: PreconditionChebyshev now offers a PreconditionChebyshev::step()
 + and PreconditionChebyshev::Tstep() methods for usage in relaxation smoothers.
 + <br>
 + (Martin Kronbichler, 2016/10/21)
 + </li>
 +
   <li> Fixed: GridIn::read_vtk() accidentally only read material ids of
   input cells correctly if the file listed them as integers. If they were
   listed them as floating point numbers, then unpredictable numbers were used.