Added extra constructor to MultiplyNode

Three arguments
Overhauled rest of engine for new DataNode overhaul (WIP)

* Moved LinearizeDepthSampleNode to the collection of basic DataNodes

* Commented-out WaterSurfaceDistortionNode until further notice.

* Temporary solution to populating the collection of node factories by
initializing the factories in SFMLOpenGLWorld::InitializeStaticSystems.
Added a PRIORITY describing a better way to do this.