Multicamviewer divided code to get user points in two methods.

This is the first step to make a easy to use tool to gather some
ground truth data
Added typedef SkeletonPtr

Substitute all boost::shared_ptr<Skeleton> for SkeletonPtr
Added typedef Skeletonization3DPtr

Added typedef for boost::shared_ptr<Skeletonization3D> now Skeletonization3DPtr is
used instead