flake8 was calling out a lot of style issues, turn those off

Pull out some useful functionality.

Useful stuff for calculating stamp sizes was put into stamp_utils.py

    get_stamp_size (was in LSST_SiliconBuilder.__init__)
        get_star_stamp_size
        get_gal_stamp_size
    get_good_phot_stamp_size (was LSST_SiliconBuilder._getGoodPhotImageSize)
    get_good_phot_stamp_size1 (was LSST_SiliconBuilder._getGoodPhotImageSize1)

Useful stuff for psfs was put into psf_utils.py

    make_double_gaussian (was LSST_SiliconBuilder.DoubleGaussian)
    make_kolmogorov_and_gaussian_psf was (LSST_SiliconBuilder.Kolmogorov_and_Gaussian_PSF)
    make_fft_psf (was LSST_SiliconBuilder.make_fft_psf)

Make optional