Moved ProgramSets to sub-package

.gitignore

library/annotation/package.scala

library/collection/package.scala

library/lang/StrOps.scala

src/main/scala/leon/codegen/CodeGeneration.scala

src/main/scala/leon/evaluators/RecursiveEvaluator.scala

src/main/scala/leon/evaluators/StringTracingEvaluator.scala

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

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

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

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

src/main/scala/leon/purescala/Extractors.scala

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

...n/scala/leon/synthesis/programsets/DirectProgramSet.scala

...ain/scala/leon/synthesis/programsets/JoinProgramSet.scala

src/main/scala/leon/synthesis/programsets/ProgramSet.scala

...in/scala/leon/synthesis/programsets/UnionProgramset.scala

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

src/main/scala/leon/utils/Library.scala