Partial implementation of call-by-name

src/main/scala/leon/frontends/scalac/ASTExtractors.scala

src/main/scala/leon/frontends/scalac/CodeExtraction.scala

...scala/leon/invariant/engine/UnfoldingTemplateSolver.scala

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

src/main/scala/leon/purescala/Definitions.scala

src/main/scala/leon/purescala/ExprOps.scala

src/main/scala/leon/purescala/MethodLifting.scala

src/main/scala/leon/purescala/PrettyPrinter.scala

src/main/scala/leon/purescala/TypeOps.scala

src/main/scala/leon/purescala/Types.scala

src/main/scala/leon/solvers/isabelle/AdaptationPhase.scala

src/main/scala/leon/solvers/smtlib/SMTLIBCVC4Solver.scala

src/main/scala/leon/solvers/smtlib/SMTLIBSolver.scala

src/main/scala/leon/solvers/smtlib/SMTLIBTarget.scala

src/main/scala/leon/solvers/z3/AbstractZ3Solver.scala

src/main/scala/leon/solvers/z3/FairZ3Solver.scala

...main/scala/leon/transformations/InstrumentationUtil.scala

src/main/scala/leon/transformations/IntToRealProgram.scala

...a/leon/transformations/NonlinearityEliminationPhase.scala

...ala/leon/transformations/SerialInstrumentationPhase.scala