Changes in ScalaBlitz for the Scala BlitzViews project

Hi guys, these changes were made during my semester project "BlitzViews" and are necessary for the next step: separating BlitzViews from the ScalaBlitz repository and using the latter as a separate dependency. The first change was made by Dmitry, the second is a small helper and the third was reviewed by Dmitry. Feel free to comment.

* Introduces a new Reducable operation: mapFilterReduce
* Add toOption for ResultCell
* Fix validateResult (remove legacy check)