Get two more TI models ready

[jlandmann]

These two models are potential candidates for the ensemble as well:

1. Giesen and Oerlemans (2012): Giesen, R. H., & Oerlemans, J. (2012). Calibration of a surface mass balance model for global-scale applications. The Cryosphere, 6(6), 1463-1481.
2. The "Alternative Temperature Index Melt Model" from : Reveillet, M., Vincent, C., Six, D., & Rabatel, A. (2017). Which empirical model is best suited to simulate glacier mass balances?. Journal of Glaciology, 63(237), 39-54.