Refactor tests: separate old from new solvers in verification

...rces/regression/verification/newsolvers/invalid/Acc.scala

...ources/regression/verification/newsolvers/valid/Acc.scala

...verification/newsolvers/valid/AddingPositiveNumbers.scala

...ession/verification/newsolvers/valid/AmortizedQueue.scala

.../regression/verification/newsolvers/valid/Anonymous.scala

...ression/verification/newsolvers/valid/ArrayLiterals.scala

...gression/verification/newsolvers/valid/ArrayUpdated.scala

...s/regression/verification/newsolvers/valid/Asserts1.scala

...ssion/verification/newsolvers/valid/AssociativeList.scala

...ression/verification/newsolvers/valid/BestRealTypes.scala

...regression/verification/newsolvers/valid/BitsTricks.scala

...egression/verification/newsolvers/valid/CaseObject1.scala

...es/regression/verification/newsolvers/valid/Choose1.scala

...s/regression/verification/newsolvers/valid/Closures.scala

.../regression/verification/newsolvers/valid/Closures2.scala

...ces/regression/verification/newsolvers/valid/Field1.scala

...ces/regression/verification/newsolvers/valid/Field2.scala

...regression/verification/newsolvers/valid/FiniteSort.scala

...es/regression/verification/newsolvers/valid/FlatMap.scala

...ssion/verification/newsolvers/valid/FoldAssociative.scala