components.CoReg.COREG:
- __init__(): added attribute 'fftw_works'
- _calc_shifted_cross_power_spectrum():
    - added fallback for fourier transformation if output is empty

components.CoReg_local.COREG_LOCAL:
- __init__(): added check if fttw transformation works
- added check_if_fftw_works()

components.Geom_Quality_Grid.Geom_Quality_Grid:
- _get_spatial_shifts(): now sets attribute 'fftw_works' before running shift calculation
- get_CoRegPoints_table(): added 'fftw_works' to kwargs for _get_spatial_shifts()

updated __version__