Simulate velocity lag

[Vinay Sriram]

We should have xml tags that allow us to ensure a velocity from a few time steps ago..

This will allow us to bring the WAM robot's simulation closer to reality and will speed up prototyping...

[Samir Menon]

I've been thinking about this, and it really isn't related to the control system. This should be ideally done by the dynamics, or by an app.

Will think about it a bit more, but I'm not sure we're going to support this feature in scl. Probably best to implement it for one's own app...