overdue refactoring (funcheck=>leon and single package)

src/main/scala/funcheck/FunCheckPlugin.scala

src/main/scala/leon/AbstractZ3Solver.scala

src/main/scala/leon/Analysis.scala

src/main/scala/leon/Annotations.scala

src/main/scala/leon/DefaultTactic.scala

src/main/scala/leon/Evaluator.scala

src/main/scala/leon/Extensions.scala

src/main/scala/leon/FairZ3Solver.scala

src/main/scala/leon/FunctionTemplate.scala

src/main/scala/leon/InductionTactic.scala

src/main/scala/leon/ParallelSolver.scala

src/main/scala/leon/RandomSolver.scala

src/main/scala/leon/Reporter.scala

src/main/scala/leon/Settings.scala

src/main/scala/leon/Stopwatch.scala

src/main/scala/leon/TestExtension.scala

src/main/scala/leon/TimeoutSolver.scala

src/main/scala/leon/Timer.scala

src/main/scala/leon/TrivialSolver.scala

src/main/scala/leon/Utils.scala