GasLiftGroupInfo.cpp did not include "config.h" which caused HAVE_MPI
to be undefined causing the file to be compiled with
Dune::Communication<No_Comm> instead of with
Dune::Communication<MPI_Comm>. Which later caused linking problems with files
that used MPI.
Check group limits in gas lift stage 1 to avoid adding too much ALQ which must
anyway later be removed in stage 2. This should make the optimization
more efficient for small ALQ increment values. Also adds MPI support.
Adds a simple test case for gas lift optimization. Currently this is
very simplistic and only covers a fraction of the gas lift optimization
code. The plan is to use this as a building block to add more tests
in the future.
