Refactor rules, remove Heuristics/Rules

src/main/scala/leon/purescala/Constructors.scala

src/main/scala/leon/repair/RepairCostModel.scala

src/main/scala/leon/repair/Repairman.scala

src/main/scala/leon/repair/rules/GuidedCloser.scala

src/main/scala/leon/repair/rules/GuidedDecomp.scala

src/main/scala/leon/synthesis/CostModel.scala

src/main/scala/leon/synthesis/Heuristics.scala

src/main/scala/leon/synthesis/PartialSolution.scala

src/main/scala/leon/synthesis/Problem.scala

src/main/scala/leon/synthesis/Rules.scala

src/main/scala/leon/synthesis/SearchContext.scala

src/main/scala/leon/synthesis/Solution.scala

src/main/scala/leon/synthesis/SynthesisContext.scala

src/main/scala/leon/synthesis/SynthesisSettings.scala

src/main/scala/leon/synthesis/Synthesizer.scala

src/main/scala/leon/synthesis/graph/DotGenerator.scala

src/main/scala/leon/synthesis/graph/Graph.scala

src/main/scala/leon/synthesis/graph/Search.scala

src/main/scala/leon/synthesis/rules/ADTDual.scala

src/main/scala/leon/synthesis/rules/ADTInduction.scala