Fixed bug with equality of non-free functions

src/it/scala/inox/TestSilentReporter.scala

.../scala/inox/solvers/unrolling/FunctionEqualitySuite.scala

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

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

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

...main/scala/inox/solvers/unrolling/DatatypeTemplates.scala

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

...main/scala/inox/solvers/unrolling/TemplateGenerator.scala

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