Added testing class for 'complex expressions', i.e. expressions that not simply generate to Java expressions but instead generate to a series of Java statements (e.g. sequence comprehensions).
Added test for generation of the 'let be st' statement (the test includes a 'be st' clause)
Added test for 'let be st' statement demonstrating how to calculate the sum of a set recursively (the test omits the 'be st' clause).
Made paths to test input files/test result files paths accessible to other parts of the testing system