* AnimInverseKinematics: debug draw for secondary targets
* AnimInverseKienmatics: better clean up of ik target debug draw
* GeometryUtil: added findPlaneFromPoints()
* ViveControllerManager: external dependency on eigen
* ViveControllerManager: record history of left/right hand controllers
* ViveControllerManager: use history to determine user shoulder location for better calibration
* ViveControllerManager: pass defaultToReferenceMat by const ref to calibrate functions.
* CMake: added external depenency to eigen linear algebra library.