added special syntax to reason about the return value of methods in the post condition, added some equivalent mutants (c# code), changed while loops to generate smaller wlp formulas if the loop does not affect the post condition

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.

side effects of left hand side in assignment handled. Side effects like this occur when assigning to arrays

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

Fixed a bug with the verification of conditional expressions. Fixed a bug with method calls on objects.