Extend lammps inputs

[ElliottKasoar]

Depends on #43 (may require rebasing)

• Converts current lammps Iterable inputs to lists of strings to reduce ambiguity, as strings are also Iterable
• Adds list typing for all integrator-specific inputs, to allow, for example, different tdamp values for different temperatures
• Adds limited validation for lengths of lists to ensure temperatures, integrators and numbers of steps are the same length
• Allows a single value to be passed (or not) for all other inputs, resulting in that value being used for all integrators
• Adds new input to allow replication in each dimension