Modification of SAMIR equations, use of Kcbmax instead of Kcmax. Plot_GIF modifications. Doc update.

Further improvements in optimization. Manage to create real empty output dataset and append values along the time dimension, greatly improves total run speed. Reworked the custom_input notebook for a better handling of the land cover class conversion. Added tests on parameters values to make sure they are in correct range, parameter ranges are defined in a csv file (params_samir_min_max.csv). Other small modifications.