Updated EquelleRuntimeCPU(grid, param) ctor to properly initialize all
members.

- This clears up the strange bug with output_to_file initialized to
random values.
- We could use delegating ctors here, that mandates the use of a
temporary grid-manager. The current implemenation returns an unmanaged
GridManager-pointer.
Added logging stream to RuntimeMPI.

- Needed for benchmarking MPI-stuff.
Merge branch 'master' of https://github.com/sintefmath/equelle