Improves syntax of Element constructor members initialization
Cleans Element class :ribbon:

* Makes getType private
* getType actually knows how to get type!
* all others, gets type using it!
* Removes unused getters/setters
Simplifies current string concatenation
Simplifies resistor test :blush:

Now, testing the Element applyStamp, not the circuit function
applyStamps.

Requires less arrangement!
Tests simple circuit stamps :princess:

Circuit: data/simples.net
Removes unused variable