Paths are broken when generating a new XYZ grid with a duplicate name

[shatteredLuigi]

If I try to generate a grid named "foo", but a folder with that name already exists, it gets renamed to "foo_old_bunchofnumbers". I don't have a problem with this in itself, but the "folder_path"s in result.json don't get updated, so they end up pointing to the new folder rather than the folder in which the JSON file resides.

I would suggest either:

• Generating a modified name for the new folder rather than renaming the old folder
• Automatically correcting the folder_paths

This issue, in combination with #69, make it a bit cumbersome to view old XYZ results. Though it's only a minor inconvenience, since I can just manually change the name every time.