Added two unit tests of the assembly of symmetric operators.
Renamed AssemblyOptions::enableSparseStorageOfMassMatrices() to
enableSparseStorageOfLocalOperators(), the old name is still supported
for backward compatibility purposes.
It is now possible to choose whether quadrature order should be uniform per
H-matrix block or not. By default it is made uniform, as in version 1.9.
Cleaned up (partly) the maxwell_dirichlet.py script.