Simplified StringTracingEvaluator.scala,

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

src/main/scala/leon/evaluators/StringTracingEvaluator.scala

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

src/main/scala/leon/purescala/ScopeSimplifier.scala

src/main/scala/leon/purescala/SelfPrettyPrinter.scala

src/main/scala/leon/synthesis/rules/StringRender.scala