Refractor MagneticFieldSensor to extend abstract class

[bartmathijssen]

This is a draft to improve the MagneticFieldSensor. I worked on extending the MagneticFieldSensor from the abstract class introduced by Ellen Spertus. This is a draft because there are still some issues. I would like your feedback on how to resolve these issues. The issue I am facing at the moment is that when using the MagneticFieldSensor, the application won't run. The issue probably lies within MultipleValueSensor class I introduced.

[barreeeiroo]

I'll take a look into it; I haven't really had time to check how the new changes to sensors work

[barreeeiroo]

@bartmathijssen I've updated the branch, so maybe you would like to take a look. I merged all the ucr changes, so there might be some changes.
Can you check if something needs to be solved?

[bartmathijssen]

@barreeeiroo I updated the branch. Unfortunately, the compiled application still won't run. There has to be something wrong with the MultipleValueSensor class, as sensors based on the SingleValueSensor class do work.

[conorshipp]

Can I ask why you've moved all of the properties from SingleValueSensor.java to SensorBase.java?

[bartmathijssen]

@conorshipp SensorBase is the base for the SingleValueSensor and MultipleValueSensor classes. As these classes have a lot in common, only the onSensorChanged method would be different.