Set shape to NULL when no collision or visual tags are given
Corrected debug message for NULL shapes
modified balance app
Change minor things.
Merge branch 'origin/master'

Conflicts:
	apps/balance/Controller.cpp
	apps/balance/Controller.h
	apps/balance/MyWindow.cpp
	src/dynamics/ConstraintDynamics.cpp
	src/simulation/SimWindow.cpp
	src/simulation/World.cpp
	src/simulation/World.h
Change minor things.
Remove unnecessary files.
Use getPose and getPoseVelocity rather than get_q and get_dq.
Remove unfinished changes.
Undo unfinished changes.
Undo unfinished changes.
Undo unfinished changes.
Merge pull request #66 from dartsim/gazebo_support

Gazebo support
Remove unnecessary files.
Remove ShapeSphere.h
Fix duplicated force input.
Remove unnecessary function (computeInvDynForces_JS).
Define NDEBUG in release mode on Linux

This speeds up some Eigen code
Some clean-up of URDF parser: Remove ability to parse object URDF files, remove double code.

More clean-up necessary.
Fix DartLoader::ParseSkeleton