Build script fixes.

- Add missing tinyxml dependency.
- Drop unnecessary Boost dependency.
- Add URDF parsing code to rosbuild.
Code consistency fixes.

- Add missing header guard.
- Make existing header guards comply with the NAMESPACE_CLASS_H convention.
- Make Doxygen structural commands start with '\' instead of '@', as most of the
  new ros_control code.
- Remove trailing whitespaces.
- Remove commented-out code used for debugging.