StringZ3 revisiter: Now the conversion is made BEFORE the solver is invoked.

src/main/scala/leon/evaluators/RecursiveEvaluator.scala

src/main/scala/leon/evaluators/StreamEvaluator.scala

src/main/scala/leon/frontends/scalac/CodeExtraction.scala

src/main/scala/leon/purescala/DefOps.scala

src/main/scala/leon/purescala/ExprOps.scala

src/main/scala/leon/purescala/Extractors.scala

src/main/scala/leon/purescala/SubTreeOps.scala

src/main/scala/leon/purescala/TypeOps.scala

src/main/scala/leon/purescala/Types.scala

src/main/scala/leon/solvers/Model.scala

src/main/scala/leon/solvers/SolverFactory.scala

...cala/leon/solvers/combinators/Z3StringCapableSolver.scala

...main/scala/leon/solvers/templates/TemplateGenerator.scala

src/main/scala/leon/solvers/templates/TemplateManager.scala

src/main/scala/leon/solvers/z3/Z3StringConversion.scala

src/main/scala/leon/utils/InliningPhase.scala

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