Break the comments to be mostly 80 chars wide, with a 100 char ceiling (mostly, probably missed some).

No actual code modification yet, only whitespace.

gprMax/snapshots.py

@@ -136,7 +136,8 @@ class Snapshot(object):
             for j in range(self.ys, self.yf, self.dy):
                 for i in range(self.xs, self.xf, self.dx):
                     pbar.update(n=12)
-                    # The magnetic field component value at a point comes from average of 2 magnetic field component values in that cell and the following cell
+                    # The magnetic field component value at a point comes from average
+                    # of 2 magnetic field component values in that cell and the following cell
                     self.filehandle.write(pack(Snapshot.floatstring, (Hx[i, j, k] + Hx[i + 1, j, k]) / 2))
                     self.filehandle.write(pack(Snapshot.floatstring, (Hy[i, j, k] + Hy[i, j + 1, k]) / 2))
                     self.filehandle.write(pack(Snapshot.floatstring, (Hz[i, j, k] + Hz[i, j, k + 1]) / 2))