Extend robot interfaces with vectorized methods

[diegoferigo]

At the moment, most of the methods part of the robot interfaces operate on a single joint and accept as argument its name.

This could be a bottleneck if used in a real-time loop, we should first profile the code and then decide if we would benefit from vectorized methods.

Note that this support should pass through the implementation of similar vectorized methods also from the C++ side. As a bonus, using vectorized methods would also save us many SWIG calls that introduce their own overhead.

[diegoferigo]

The new ScenarI/O APIs #158 have been designed to fully support vectorization. Closing.