checked wishnu's mutations and applies manual preprocessing/desugaring where needed. Also fixed a bug where introduced variables in the wlp would result in an error (introduced variables may be part of the wlp when the code contains non-void functions that don't terminate within the set limit of iterations)

WLP is now calculated for every method seperately, instead of just for the main method. The code for filling the type environment is now seperated from the rest of the program.

seperated side effects from expressions by introducing variables for guards and expressions with operators