Cleaning up useless files

examples/game2048/build.sbt

examples/game2048/index.html

examples/game2048/project/plugins.sbt

...ples/game2048/src/main/scala/leon/game2048/Game2048.scala

examples/game2048/src/main/scala/leon/game2048/Main.scala

examples/gametictactoe/build.sbt

examples/gametictactoe/index.html

examples/gametictactoe/project/plugins.sbt

...toe/src/main/scala/leon/gametictactoe/GameTicTacToe.scala

...ametictactoe/src/main/scala/leon/gametictactoe/Main.scala

library/leon/annotation/isabelle.scala

library/leon/annotation/package.scala

library/leon/collection/List.scala

library/leon/collection/package.scala

library/leon/instrumentation/package.scala

library/leon/invariant/package.scala

library/leon/io/StdIn.scala

library/leon/lang/Bag.scala

library/leon/lang/Dummy.scala

library/leon/lang/Either.scala