Update calibration settings

I updated the adamgreen.config files for the second sensor board that
I built up this week.  I also added placeholder xandon.config files
which contain the calibration settings used for the sensor board that
he has.
Add ConfigFile to magView sample
Add ConfigFile to filterPlay sample
Manage Serial object in HeadingSensor class

Previously the main compass application object instantiated the Serial
port object, passed it into the HeadingSensor class constructor, and
later captured serial events and forwarded them to the HeadingSensor
child object as well.  Now the HeadingSensor object takes care of all
Serial object maintenance itself.
Create FilteredCompass class

This class provides all of the current tilt compensated compass
functionality and removes it from the high level application itself.