Task space feature

This PR continues PR #210 but with the source moved into the simbody/simbody repo from chrisdembia/simbody. (via short-lived PR #237). This is so Chris and I can work on it together and with osrf.

cc/ @chrisdembia @hsu @scpeters 
If CMAKE_INSTALL_PREFIX is a relative path, then this won't work I think. However, there are other places in which we assume CMAKE_INSTALL_PREFIX is an absolute path. 

If you do decide to fix this: http://www.cmake.org/pipermail/cmake/2009-June/030237.html