Update to use QuantityNode, also use safer methods.
Update to use QuantityNode, also use safer methods.

Replacing static_cast of pointers with dynamic_cast of references.

babrodtk/equelle,babrodtk/equelle,atgeirr/equelle,sintefmath/equelle,atgeirr/equelle,atgeirr/equelle,babrodtk/equelle,sintefmath/equelle,sintefmath/equelle,atgeirr/equelle,babrodtk/equelle,sintefmath/equelle,babrodtk/equelle,atgeirr/equelle,atgeirr/equelle,sintefmath/equelle,sintefmath/equelle,atgeirr/equelle,sintefmath/equelle,sintefmath/equelle,babrodtk/equelle,atgeirr/equelle,babrodtk/equelle