Extend MetaSkeletonStateSaver to more than just positions

[mkoval]

#184 added a MetaSkeletonStateSaver RAII class that can be used to save and restore a MetaSkeleton's positions. This is a good start, but is ultimately insufficient for all of the types of state that we modify in manipulation tasks (e.g. grabbed objects, geometry padding, etc).

Once we have more experience using Aikido, we should revisit this issue and extend MetaSkeletonStateSaver - or write a new class altogether - that handles this more general case. The approach we took in Magi, i.e. writing "actions" that know how to undo themselves, could prove fruitful.

[jslee02]

Update: added joint limits in #219