Move class Handle from hpp-manipulation

[jmirabel]

It would be a good idea to think of moving class Handle from the manipulation stack to this package. The frames would become accessible from the hpp-corbaserver package.

[nmansard]

Not mandatory for passing from hpp::model to pinocchio.

[florent-lamiraux]

After considering it, the main property of class hpp::manipulation::Handle is to create constraints.
And constraints are defined in hpp-constraints, but not in hpp-pinocchio.