Nicer transformers

src/main/scala/inox/Program.scala

src/main/scala/inox/ast/Definitions.scala

src/main/scala/inox/ast/Identifier.scala

src/main/scala/inox/ast/ProgramEncoder.scala

src/main/scala/inox/ast/TreeOps.scala

src/main/scala/inox/ast/TypeOps.scala

src/main/scala/inox/solvers/theories/BagEncoder.scala

src/main/scala/inox/solvers/theories/StringEncoder.scala

src/main/scala/inox/solvers/theories/TheoryEncoder.scala

src/main/scala/inox/solvers/unrolling/UnrollingSolver.scala

src/main/scala/inox/solvers/z3/NativeZ3Solver.scala