Remove unused imports

src/main/scala/leon/LeonContext.scala

src/main/scala/leon/Reporter.scala

src/main/scala/leon/codegen/CodeGenPhase.scala

src/main/scala/leon/codegen/CompiledExpression.scala

src/main/scala/leon/codegen/runtime/GenericValues.scala

src/main/scala/leon/datagen/NaiveDataGen.scala

src/main/scala/leon/evaluators/CodeGenEvaluator.scala

...main/scala/leon/frontends/scalac/AddTypeAnnotations.scala

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

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

...in/scala/leon/purescala/CompleteAbstractDefinitions.scala

src/main/scala/leon/purescala/Constructors.scala

src/main/scala/leon/purescala/Definitions.scala

src/main/scala/leon/purescala/FunctionMapping.scala

src/main/scala/leon/purescala/PrettyPrinter.scala

src/main/scala/leon/purescala/ScalaPrinter.scala

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

src/main/scala/leon/purescala/TreeNormalizations.scala

src/main/scala/leon/purescala/Trees.scala

src/main/scala/leon/repair/RepairCostModel.scala