Add options in Construct_SLX_with_NN for model_name and block_name

[nikos-kekatos]

The construct_SLX_with_NN function is used to integrate the neural net (with the name options.NN_model) with the Simulink model that contains two closed-loop models (options.SLX_NN_model). We need to have

• default options for block_name (NN)

• default option for the Simulink model file (originalName_NN.slx)
  options.SLX_NN_model=strcat(options.SLX_model,'_NN')

• add options for inputs to the function

• check consistency in all places it is called.