reorganize verification testcases

testcases/verification/Errors.scala

testcases/verification/MutuallyRecursive.scala

testcases/verification/algorithms/FiniteSort.scala

testcases/verification/algorithms/SecondsToTime.scala

testcases/verification/list-algorithms/Sorting.scala

testcases/verification/list-algorithms/SumAndMax.scala

...cases/verification/list-algorithms/TwoSizeFunctions.scala

testcases/verification/math/Fibonacci.scala

testcases/verification/math/Naturals.scala

testcases/verification/math/Prime.scala

testcases/verification/math/PropositionalLogic.scala

testcases/verification/xlang/Arithmetic.scala

...s/verification/xlang/master-thesis-regis/Arithmetic.scala

...rification/xlang/master-thesis-regis/ListOperations.scala