Adding coversion from eager to lazy, seperating verification

library/lazy/package.scala

src/main/scala/leon/invariant/datastructure/Graph.scala

src/main/scala/leon/invariant/util/CallGraph.scala

src/main/scala/leon/invariant/util/TreeUtil.scala

src/main/scala/leon/laziness/LazinessEliminationPhase.scala

src/main/scala/leon/laziness/LazinessUtil.scala

src/main/scala/leon/laziness/LazyClosureConverter.scala

src/main/scala/leon/laziness/LazyClosureFactory.scala

src/main/scala/leon/laziness/LazyInstrumenter.scala

src/main/scala/leon/laziness/TypeChecker.scala

src/main/scala/leon/laziness/TypeRectifier.scala

testcases/lazy-datastructures/BottomUpMegeSort.scala

testcases/lazy-datastructures/RealTimeQueue.scala