Testcases for higher-order functions

...es/verification/higher-order/invalid/Continuations1.scala

...ses/verification/higher-order/invalid/HOInvocations.scala

testcases/verification/higher-order/invalid/Lists1.scala

testcases/verification/higher-order/invalid/Map.scala

testcases/verification/higher-order/invalid/ParBalance.scala

...cases/verification/higher-order/invalid/PositiveMap.scala

testcases/verification/higher-order/invalid/Sets1.scala

testcases/verification/higher-order/valid/Anonymous.scala

testcases/verification/higher-order/valid/Closures.scala

testcases/verification/higher-order/valid/Closures2.scala

testcases/verification/higher-order/valid/FlatMap.scala

...ses/verification/higher-order/valid/FoldAssociative.scala

...cases/verification/higher-order/valid/HOInvocations.scala

testcases/verification/higher-order/valid/Lambdas.scala

testcases/verification/higher-order/valid/Lists1.scala

testcases/verification/higher-order/valid/Lists2.scala

testcases/verification/higher-order/valid/Lists3.scala

testcases/verification/higher-order/valid/Lists4.scala

testcases/verification/higher-order/valid/Lists5.scala

testcases/verification/higher-order/valid/Lists6.scala