Reversed splines

[CarlinWilliamson]

resolves #176

Adds the ability to plot reverse splines (where the robot drives backwards)

These are indicated by a dashed line and can be toggled using the right click menu on the waypoints.

[CarlinWilliamson]

Things I don't like here:

• My testing has only gone as far as observing the json files of the same path when reversed and not reversed
• This involved adding a boolean property to every waypoint (avoiding significant changes to PathIOUtil.java) which is unintuative at best
• The right click menu for toggling the direction is on the waypoints not the spline itself
• Reversed is not included in the "waypoint properties" menu (it should really be in a path properties menu)

I should have access to a robot to test this in a few days.

My suggestion for fixing this boolean property issue would be to rework PathIOUtil to use json (so you can have properties for the path not the waypoints), move the right click menu to the spline and create a "path properties" menu. Looks like a fair bit of work... Perhaps it should go in a seperate PR? Thoughts?

[Daltz333]

Your suggestions seem like a fair idea. Unfortunately, dev momentum on this project is pretty bare-bones. I would continue forward, and when it's ready for review, we can at least test the changes and see about merging then.

[CarlinWilliamson]

I did end up adding resverse splines to the "waypoint properties" menu. Tested it tonight and I'm happy with things.