replaces RigidBodyManipulator pointer data with Eigen and std container classes

... in an attempt to robustify our memory management.  Tried to follow the instructions from here:
http://eigen.tuxfamily.org/dox-devel/group__TopicStlContainers.html

Please check my work carefully!

Also introduces a warnOnce feature and a few minor fixes that I made while trying to debug this from drake-distro/minimal .  (sorry - this perhaps should have been in a separate pull)