Finished up unrolling solver and theory encoders

src/main/scala/inox/ast/DSL.scala

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

src/main/scala/inox/ast/Expressions.scala

src/main/scala/inox/ast/Extractors.scala

src/main/scala/inox/ast/GenTreeOps.scala

src/main/scala/inox/ast/Printers.scala

src/main/scala/inox/ast/SymbolOps.scala

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

src/main/scala/inox/ast/Trees.scala

src/main/scala/inox/evaluators/RecursiveEvaluator.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

...main/scala/inox/solvers/unrolling/FunctionTemplates.scala

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