SetupRHSforTDCSandTMS as well as fix for mapping field data 

SetupRHSforTDCSandTMS obtains electrode values now with loops. A check makes sure the data is not sent out of order, otherwise an algorithm processing exception gets thrown.

The mapping field data now returns the input as the output when the data is on the respective nodes or elements.
This section could be tighter: extract a function called initialElectrodeValue(int row) and then call that instead of switching here. And better to push it down to the algorithm class as another static method.