Made methods in LinearFilter virtual so they can be overloaded in
sub-classes
Implementing Rotation in OdometryFilter

Added an overloaded version of the update method to OdometryFilter which
rotates the input/measurement values to the odometry frame using
rotation matricies built from the last state estimate

#1
Constructor refactoring / OdometryFilter addition

Refactored the constructor for KVHDriverNode to call numerous
intializaiton methods that handle doing all of the various components of
node construction instead of it all being in a single monolithic
constructor. This improves code readability and debugability.

Also added construction of an odometry filter to KVHDriverNode for
testing  #1, although it is currently not used for anything