Fixes plot bug when resample is set on a subset of contrast

[StephenNneji]

Bug can be reproduced by running the DSPC_standard_layers example with resample set to True on the first contrast only i.e.

    # Then make the two contrasts
    problem.contrasts.append(
        name="D2O",
        bulk_in="Silicon",
        bulk_out="D2O",
        background="D2O Background",
        resolution="Resolution 1",
        scalefactor="Scalefactor 1",
        data="dspc_bil_D2O",
        resample=True,
        model=stack,
    )

    problem.contrasts.append(
        name="SMW",
        bulk_in="Silicon",
        bulk_out="SMW",
        background="SMW Background",
        resolution="Resolution 1",
        scalefactor="Scalefactor 2",
        data="dspc_bil_smw",
        model=stack,
    )

The plot function will crash as it assumes resample is set on all or no contrast, this is fixed by this PR

Also moved a few thing out of setup.py