handle different wavelength ranges
handle different wavelength ranges

- If the range of wavelengths overlaps with the visible light range then use bands that are close to wavelength size, but if the spectral camera has a different (e.g. infrared or ultraviolet) then we still want to be able to plot a pseudo_rgb image. Handle the case where none of the wavelengths are in the visible range.

danforthcenter/plantcv,danforthcenter/plantcv,danforthcenter/plantcv,stiphyMT/plantcv,stiphyMT/plantcv,stiphyMT/plantcv