message: Adding sample runs
diff: // Hertz Miniapp: Simple Frequency-Domain Electromagnetic Simulation Code
  // -----------------------------------------------------------------------
  //
  +// Compile with: make hertz
  +//
  +// Sample runs:
  +//
  +// By default the sources and fields are all zero
  +// mpirun -np 4 hertz
  +//
  +// Current source in a sphere with absorbing boundary conditions
  +// mpirun -np 4 hertz -m ../../data/ball-nurbs.mesh -rs 2
  +// -abcs '-1'
  +// -do '-0.3 0.0 0.0 0.3 0.0 0.0 0.1 1 .5 .5'
  +//
  +// Current source in a metal sphere with dielectric and conducting materials
  +// mpirun -np 4 hertz -m ../../data/ball-nurbs.mesh -rs 2
  +// -dbcs '-1'
  +// -do '-0.3 0.0 0.0 0.3 0.0 0.0 0.1 1 .5 .5'
  +// -cs '0.0 0.0 -0.5 .2 10'
  +// -ds '0.0 0.0 0.5 .2 10'
  +//
  +// Current source in a metal box
  +// mpirun -np 4 hertz -m ../../data/fichera.mesh -rs 3
  +// -dbcs '-1'
  +// -do '-0.5 -0.5 0.0 -0.5 -0.5 1.0 0.1 1 .5 1'
  +//
  +// Current source with a mixture of absorbing and reflecting boundaries
  +// mpirun -np 4 hertz -m ../../data/fichera.mesh -rs 3
  +// -do '-0.5 -0.5 0.0 -0.5 -0.5 1.0 0.1 1 .5 1'
  +// -dbcs '4 8 19 21' -abcs '5 18'
  +//
  #include "hertz_solver.hpp"
  #include <fstream>
  