* working on cmake config

bh_tree_mpi/datastructures/CMakeLists.txt

 file( GLOB datastructures_SOURCES *.hpp *.cpp )
-add_library( datastructures ${datastructures_SOURCES} )
\ No newline at end of file
+add_library( datastructures ${datastructures_SOURCES} )

bh_tree_mpi/simulation/CMakeLists.txt

 file( GLOB simulation_SOURCES *.hpp *.cpp )
 include_directories(../datastructures)
-add_library( simulation ${simulation_SOURCES} )
\ No newline at end of file
+add_library( simulation ${simulation_SOURCES} )
+target_link_libraries(simulation datastructures ${MPI_LIBRARIES})
\ No newline at end of file