DUI: icons dynamo units(logic)

This PR includes additional logic for Units category.
What is interesting - Units have methods like Operators(e.g. +,%,>, etc.), but these methods are overloaded. So, logic was rewritten a little bit. So that, we can use overloaded operators.

# Reviewers
@Benglin,@vmoyseenko, please take a look.
Both the ```cases``` in this ```switch``` statement are exactly the same, merge them into one.