`create.py` only lets you create a new IN.DAT from the first point in a scan

[j-a-foster]

After running a scan with 31 points, I couldn't create a new IN.DAT from an input file other than the very first point, even with using the -fpi argument.

When looking at create.py I believe it's due to the feasible_point method scanning over mfile values rather than scan points.

[timothy-nunn]

@j-a-foster I have seen you have created a branch for this so have assigned you. If you are not actively working on fixing this bug please unassign yourself