mol4ub/SAMM_model: SAMM version 1.1

This is version 1.1 of the SAMM model, a corrected version of the article submitted in the article "SAMM - A numerical model for microbial mediated soil aggregate formation." to Geoscientific Model Development.

The main change is the correction of a unit error in calculating MAO_C_max. 

The upload consist of the following:

• the R code to execute the model, including all model equations
• a climate file that includes all external drivers needed to run the model for the Khon Kaen site (derived by HYDRUS 1D from measured precipitation nearby)
• the data used to calibrate the model