Exclude water from max number of bonds calculation

The LAMMPS interface requires that the maximum number of bonds/angles/dihedrals/impropers that any atom possesses is defined upon box creation, so that the memory can be allocated in advance of these bonds etc being defined.

Currently this is achieved by simply determining all of these for each atom; however it is likely that in a simulation the majority of atoms will be in water molecules. As the number of bonds etc is known for all atoms in a water molecule, this can simply be included in the max calculation without calculation the bonds etc for all of these atoms.