Reverse route option

[davecraig]

From a user:

I would like to be able to reverse a route that I have created

There are at least two ways of doing this:

1. Add the option to playback a route in reverse, or
2. Add being able to create a copy of a route that's reversed (or even not-reversed, if a user wants to start off from a route and vary it).

The first option would mean that any changes in a route only have to happen in one place, but it might be that the user does want a slightly different route back and so both options are probably required.