IRIS instruments have too small of a spectral window

[jwreep]

The IRIS instruments currently bundled in Forward_Model have only three points in wavelength space, meaning that the line shapes can't be synthesized from them.

I've attached the full IRIS response functions here. The instrument files should be suitably modified to include a larger window in wavelength.

iris_response_function_fuv1.txt
iris_response_function_fuv2.txt
iris_response_function_nuv.txt