Restart in libMesh

Check libMesh restart capabilities.

Based on adaptivity_ex5.

requirements

libMesh should be configured with mpi, petsc and exodusII support.

Using spack:

spack install libmesh@master +mpi +petsc +exodusii

libMesh is found via pkgconfig, so make sure to have its folder available:

export PKG_CONFIG_PATH=$LIBMESH_DIR/lib[64]/pkgconfig