diff_drive: clean and comments code that sets the wheels velocities
diff_drive: add speed limiter for velocity and acceleration limits
diff_drive: remove struct for linear and angular SpeedLimiter objects
diff_drive: change 'Willow Garage' to 'PAL Robotics' in the license
diff_drive: format SpeedLimiter constructor to avoid long lines
diff_drive: fix copyright notice
diff_drive: factorize (future) common code in tests
diff_drive: factorize (future) common launch files in tests
diff_drive: fix indentation of yaml file
diff_drive: add parameter file for limits in tests
diff_drive: fix acceleration limit

The dt was wrong.
diff_drive: add unit test for velocity and acceleration limits
diff_drive: small fix in SpeedLimiter doc
diff_drive: cosmetic fix

For a comment, in a launch file, for a unit test.
Quite the commit, right?
Merge pull request #19 from po1/diff-drive-limits

Diff drive task space limits for velocity and acceleration