finalizing mesh walls and lammps

[jadhao]

@nasimanousheh will comment out the explicit mesh LJ walls for accurate/faster code. 1st and 2nd step
@nasimanousheh get the mesh discretization to match with dummy wall for lammps grid. at some point, we fix the grid for a broad range of c.

[jadhao]

@nasimanousheh @kadupitiya
I have gone ahead and removed the LJ mesh - ion interaction completely from forces and energies.
Please check. I have not tested or compiled this in the interest of time; so there may be bugs!!
Please re-check with old data, say for default. Densities should be very similar for the default settings as dummy walls dominate the LJ forces arising from mesh.
Please confirm things are fine or if there are problems. Then I will close this issue after proper resolution.

[kadupitiya]

@jadhao: I submitted a simulation and I will let you know once that is finished.

[nasimanousheh]

@jadhao and @kadupitiya;
I checked the energy and density profiles. The results are comparable with old ones.