Merge branch 'picking' into 'master'

Base/Collision/CollisionData/imstkCollisionData.h

.../Collision/CollisionDetection/imstkCollisionDetection.cpp

Base/Collision/CollisionDetection/imstkCollisionDetection.h

...llision/CollisionDetection/imstkMeshToSpherePickingCD.cpp

...Collision/CollisionDetection/imstkMeshToSpherePickingCD.h

Base/Collision/CollisionHandling/imstkCollisionHandling.cpp

Base/Collision/CollisionHandling/imstkCollisionHandling.h

Base/Collision/CollisionHandling/imstkPickingCH.cpp

Base/Collision/CollisionHandling/imstkPickingCH.h

Base/Collision/imstkInteractionPair.cpp

Base/Collision/imstkInteractionPair.h

...traint/PbdConstraints/imstkLinearProjectionConstraint.cpp

...nstraint/PbdConstraints/imstkLinearProjectionConstraint.h

Base/Core/imstkAPIUtilities.h

Base/Scene/imstkCollisionGraph.cpp

Base/Scene/imstkCollisionGraph.h

Base/Solvers/imstkConjugateGradient.cpp

Base/Solvers/imstkConjugateGradient.h

Base/Solvers/imstkNewtonSolver.cpp

Base/Solvers/imstkNonlinearSystem.h