Improved comment + fixing some bug

openfpm_data.doc

src/Grid/comb.hpp

src/Grid/grid_key.hpp

src/Grid/grid_sm.hpp

src/Grid/grid_unit_tests.hpp

src/NN/CellList/CellDecomposer.hpp

src/NN/CellList/CellList.hpp

src/NN/CellList/CellListBal.hpp

src/NN/CellList/CellListFast.hpp

src/NN/CellList/CellList_test.hpp

src/NN/CellList/CellNNIterator.hpp

src/Space/Shape/Box.hpp

src/Space/Shape/HyperCube.hpp

src/Space/SpaceBox.hpp

src/Space/SpaceBox_unit_tests.hpp

src/Vector/map_vector.hpp

src/Vector/map_vector_std.hpp

src/common.hpp