alpha release

this is a very preliminary effort to learn about CERES-RICE model's working and to explore the limit of code manipulation.
the model will only simulate Rice growth under SRI. There should be a switch named "ISSRI" present in X file after CO2 switch to simulate SRI. else the simulation will be the same as original model. At present ISSRI accepts only 'Y'. the modifications carried out are specific to our particular study. the normal operation of model is no way affected by our modifications.