Apply BSD 2 clauses license

src/main/scala/leon/z3plugins/bapa/PrettyPrinter.scala

src/main/scala/leon/z3plugins/bapa/VennRegions.scala

...regression/verification/purescala/error/InstanceOf1.scala

...s/regression/verification/purescala/invalid/Choose1.scala

...egression/verification/purescala/invalid/FiniteSort.scala

...ession/verification/purescala/invalid/InsertionSort.scala

...ssion/verification/purescala/invalid/ListOperations.scala

.../regression/verification/purescala/invalid/MyTuple1.scala

.../regression/verification/purescala/invalid/MyTuple2.scala

.../regression/verification/purescala/invalid/MyTuple3.scala

...n/verification/purescala/invalid/PropositionalLogic.scala

...ression/verification/purescala/invalid/RedBlackTree.scala

...ces/regression/verification/purescala/invalid/Unit1.scala

...ression/verification/purescala/valid/AmortizedQueue.scala

...ession/verification/purescala/valid/AssociativeList.scala

...gression/verification/purescala/valid/BestRealTypes.scala

...regression/verification/purescala/valid/CaseObject1.scala

...ces/regression/verification/purescala/valid/Choose1.scala

...rces/regression/verification/purescala/valid/Field1.scala

...rces/regression/verification/purescala/valid/Field2.scala