simulated autonomous driving with ROS

[Jack O'Quin]

I set a bunch of tuning parameters from the Player navigator.cfg files
and renamed the launch file auto_stage.launch (from nav_stage).

The car now drives pretty well on the simulated swri_site_visit map,
except for U-turns (which are broken), passing and zones (which are
not implemented at all). In general, it does not handle rejoining a
lane, but it follows lanes fairly well now. There is absolutely no
sensor input to the navigator at this time, the car is driving blind.

This also depends on fixing the ROS stage package to handle the
wheelbase parameter for cars. Without that fix it simulates a 1.0
meter wheelbase, which implies a very short turning radius. (See ros-
pkg ticket #4099).

This fix is now committed in ros-pkg and released for cturtle. The ros-
cturtle-simulator-stage binary package update should appear some time
within the next week. If you want to simulate the vehicle steering
accurately before then, check out the package from SVN...

https://code.ros.org/svn/ros-pkg/stacks/simulator_stage/trunk

Then add it to your $ROS_PACKAGE_PATH and rosmake art_nav, which
depends on it. If you need help doing all that, ask for more detailed
directions. Most people can probably wait until the binary package
update arrives.