SimpleSetup Improvements

Moved useful features from Lightning to SimpleSetup while I was making Lightning inherit from SS:

- New function to access a solution's planner name, corresponding to new feature https://github.com/ompl/ompl/pull/11
- Handle to set a custom optimization objective
- Formatting fix where ``last_status_`` should be camel case
- ``simplifySolution()`` debug output now tells user how many states where removed
The problem with that is there currently is no getter for the actual solution's PlannerData object. I first tried to create one, but I ran into lots of issues that we discussed at the time and, I forgot why, but it was not a good idea. Your change won't currently work the way things are configured - the only access to the solution we have is in getting the *path*