Adds a very unrealistic setup that can be used to test the iceberg removal code.
It works!
Removes old iceberg elimination code.

Also:
- removes an old unused temporary storage (IceModel::vWork2dV)
- adds an extra sanity check to SSAFD::assemble_matrix()
- removes the "-vpik" options
- connected_components.{cc,hh} matches the stand-alone version
  again (to simplify regression testing)
Do not allocate PISMIcebergRemover unless "kill_icebergs" is set.
Closes #154.

  (Make sure that PISM can start from a file *without* the Href field.)

  https://github.com/pism/pism/issues/154
Merge branch 'new-iceberg-remover' into dev