New issue found at cold temperatures (<50K) linked with defaut value of NTstar=500

[sglmd]

With NTstar set at 500 (the default value, defined in radinc_h.F90), the planck function is integrated starting from 50K in setspi.F90.

But then, in sfluxi.F90 and gfluxi.F90, the second index in the planckir array can take a value lower than 1 if the temperature is lower than 50K, and the code crashes.
Example of index: planckir:(NW, TLEV(2L) * NTfac -NTstar +1)
(with NTfac=10)

One solution is to set NTstar at a lower value (eg, 300) but for hot jupiter for instance, it would add a bit of computation time (as the array planckir would be a bit bigger) for nothing.
Solution: add error message if the temperature is lower than NTstar/NTfac?

[jvatant]

Fixed with r2283