Merge branch 'feature/item-array' into 'develop'

src/mesh/Connectivity.cpp

src/mesh/Connectivity.hpp

src/mesh/ConnectivityDispatcher.cpp

src/mesh/IConnectivity.hpp

src/mesh/ItemArray.hpp

src/mesh/ItemArrayUtils.hpp

src/mesh/ItemValue.hpp

src/mesh/ItemValueUtils.hpp

src/mesh/Mesh.hpp

src/mesh/SubItemArrayPerItem.hpp

src/mesh/SubItemValuePerItem.hpp

src/mesh/Synchronizer.hpp

src/output/GnuplotWriter1D.cpp

src/utils/SubArray.hpp

tests/CMakeLists.txt

tests/test_ItemArray.cpp

tests/test_ItemArrayUtils.cpp

tests/test_ItemValue.cpp

tests/test_ItemValueUtils.cpp

tests/test_SubArray.cpp