Moved the library/ to library/leon/ so that IDE do not complain.

library/leon/lazy/package.scala

library/leon/math/package.scala

library/leon/mem/package.scala

library/leon/monads/state/State.scala

library/leon/par/package.scala

library/leon/proof/Internal.scala

library/leon/proof/package.scala

library/leon/stats/package.scala

library/leon/theories/Bag.scala

library/leon/theories/String.scala

library/leon/util/Random.scala