Add spinel optical constants to reference data

# Spinel (MgAl2O4) according to Fabian+2001 (DOI:10.1051/0004-6361:20010657)

#

# Wavelengths are in meters.

#

#Wavelength,Re(EPS),Im(EPS)

1.0000e-06,2.87302e+00,2.3052e-04

2.5000e-06,2.81331e+00,4.9883e-04

3.4542e-06,2.74108e+00,1.3672e-03

4.3975e-06,2.64307e+00,2.9712e-03

5.3505e-06,2.51350e+00,5.7297e-03

6.2500e-06,2.35816e+00,9.9070e-03

7.3046e-06,2.12610e+00,1.7856e-02

8.3472e-06,1.82852e+00,3.1165e-02

9.3897e-06,1.43761e+00,5.4837e-02

1.0277e-05,0.99720e+00,9.2989e-02

1.1249e-05,0.33492e+00,1.9332e-01

1.2019e-05,-0.35290e+00,4.5157e-01

1.2563e-05,-0.73138e+00,6.6699e-01

1.3021e-05,-1.29085e+00,6.5761e-01

1.3441e-05,-2.15452e+00,7.9645e-01

1.3966e-05,-3.81662e+00,1.4652e+00

1.4347e-05,-5.70823e+00,3.0263e+00

1.4518e-05,-6.66839e+00,4.5679e+00

1.4684e-05,-7.19795e+00,7.3031e+00

1.4815e-05,-6.30998e+00,1.0273e+01

1.5015e-05,-0.89579e+00,1.3162e+01

1.5152e-05,3.02557e+00,1.1435e+01

1.5337e-05,4.74121e+00,7.4929e+00

1.5504e-05,4.25754e+00,5.0383e+00

1.5873e-05,2.19623e+00,2.6082e+00

1.6367e-05,-0.17548e+00,1.7214e+00

1.6611e-05,-1.27090e+00,1.6460e+00

1.7065e-05,-3.61691e+00,2.3187e+00

1.7212e-05,-4.15321e+00,3.4340e+00

1.7331e-05,-3.34496e+00,4.2263e+00

1.7452e-05,-2.73775e+00,3.4082e+00

1.7668e-05,-3.90035e+00,2.4700e+00

1.7986e-05,-5.92752e+00,2.5438e+00

1.8484e-05,-9.43218e+00,3.6638e+00

1.9011e-05,-1.44646e+01,6.4885e+00

1.9418e-05,-1.97257e+01,1.1429e+01

1.9685e-05,-2.33986e+01,1.7541e+01

1.9920e-05,-2.52840e+01,2.5783e+01

2.0202e-05,-2.30193e+01,3.7738e+01

2.0534e-05,-1.76878e+01,5.2234e+01

2.0877e-05,1.53007e+01,8.0516e+01

2.1186e-05,5.08954e+01,4.4945e+01

2.1645e-05,3.97004e+01,1.5790e+01

2.2026e-05,3.18734e+01,8.9270e+00

2.2573e-05,2.52758e+01,5.0333e+00

2.3419e-05,1.98098e+01,2.7421e+00

2.4213e-05,1.69026e+01,1.8258e+00

2.5000e-05,1.50063e+01,1.3379e+00