adding a package and example code on generating walking gaits for planar bipeds.
The package is still under development and is a restrictive version of what the
underlying code base can do with respect to gaits for bipeds in general.
Eventually the restriction on gaits placed by the package and documentation in
general will be added over time.  The package is still useful and pretty stable.
It is the ideal place to start when learning to use the NLinks and Continuation
packages.