Add ShapeSphere.
Create collision detectior interface.
Add new fcl collition detector. (mesh and primitives)
Keep old fcl collision detector. (always mesh-mesh)
Merge branch 'origin/master'

Conflicts:
	src/robotics/World.cpp
Resolve complie errors.
Use mesh-mesh collision detection only in ConstraintDynamics.
Merge branch 'origin/master'
Merge branch 'origin/master'
Merge branch 'origin/primitive_collision'

Conflicts:
	apps/balance/Controller.cpp
	apps/hanging/Controller.cpp
	apps/hanging/MyWindow.cpp
	apps/hardcodedDesign/MyWindow.h
	apps/meshCollision/MyWindow.cpp
	apps/meshCollision/MyWindow.h
	apps/spheres/Main.cpp
	src/collision/CollisionDetector.cpp
	src/collision/CollisionDetector.h
	src/collision/CollisionNode.cpp
	src/collision/CollisionNode.h
	src/collision/fcl/FCLCollisionDetector.cpp
	src/collision/fcl/FCLCollisionDetector.h
	src/collision/fcl/FCLCollisionNode.cpp
	src/collision/fcl/FCLCollisionNode.h
	src/collision/fcl/tri_tri_intersection_test.h
	src/collision/fcl_mesh/tri_tri_intersection_test.h
	src/collision/tri_tri_intersection_test.h
	src/dynamics/ConstraintDynamics.cpp
	src/dynamics/ConstraintDynamics.h
	src/dynamics/ContactDynamics.cpp
	src/dynamics/ContactDynamics.h
	src/kinematics/Skeleton.cpp
	src/kinematics/Skeleton.h
	src/simulation/SimWindow.cpp