Apply BSD 2 clauses license

src/main/scala/leon/verification/AnalysisPhase.scala

src/main/scala/leon/verification/DefaultTactic.scala

src/main/scala/leon/verification/InductionTactic.scala

src/main/scala/leon/verification/Tactic.scala

src/main/scala/leon/verification/VerificationCondition.scala

src/main/scala/leon/verification/VerificationContext.scala

src/main/scala/leon/verification/VerificationReport.scala

src/main/scala/leon/xlang/ArrayTransformation.scala

src/main/scala/leon/xlang/EpsilonElimination.scala

src/main/scala/leon/xlang/FunctionClosure.scala

src/main/scala/leon/xlang/ImperativeCodeElimination.scala

src/main/scala/leon/xlang/TreeOps.scala

src/main/scala/leon/xlang/Trees.scala

src/main/scala/leon/xlang/XlangAnalysisPhase.scala

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

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

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

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

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

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