Adding support for verifying programs with laziness

library/annotation/package.scala

library/lazy/package.scala

src/main/scala/leon/Main.scala

src/main/scala/leon/invariant/structure/FunctionUtils.scala

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

...n/scala/leon/invariant/util/LetTupleSimplifications.scala

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

src/main/scala/leon/purescala/Expressions.scala

src/main/scala/leon/purescala/PrinterHelpers.scala

...scala/leon/transformations/LazinessEliminationPhase.scala

...cases/lazy-datastructures/RealTimeQueue-transformed.scala

testcases/lazy-datastructures/RealTimeQueue.scala