Make testing compatible with Eclipse + ScalaTest

src/test/scala/leon/test/LeonTestSuite.scala

src/test/scala/leon/test/TestSilentReporter.scala

src/test/scala/leon/test/evaluators/EvaluatorsTests.scala

src/test/scala/leon/test/purescala/DataGen.scala

src/test/scala/leon/test/purescala/LikelyEq.scala

src/test/scala/leon/test/purescala/LikelyEqSuite.scala

src/test/scala/leon/test/purescala/TransformationTests.scala

...t/scala/leon/test/purescala/TreeNormalizationsTests.scala

src/test/scala/leon/test/purescala/TreeOpsTests.scala

src/test/scala/leon/test/purescala/TreeTests.scala

...test/scala/leon/test/solvers/EnumerationSolverTests.scala

src/test/scala/leon/test/solvers/TimeoutSolverTests.scala

src/test/scala/leon/test/solvers/z3/FairZ3SolverTests.scala

.../scala/leon/test/solvers/z3/FairZ3SolverTestsNewAPI.scala

...ala/leon/test/solvers/z3/UninterpretedZ3SolverTests.scala

src/test/scala/leon/test/synthesis/AlgebraSuite.scala

...test/scala/leon/test/synthesis/LinearEquationsSuite.scala

.../scala/leon/test/synthesis/SynthesisRegressionSuite.scala

src/test/scala/leon/test/synthesis/SynthesisSuite.scala

...t/scala/leon/test/termination/TerminationRegression.scala