Allow to change order (navigator becomes driver vs. driver becomes navigator)

[haraldreingruber]

There are different opinions about the pros and cons of either direction. It would be great to have the rotation direction configurable to allow experimenting with it easily.

A simple approach might be just inverting the rotation direction.

Another idea would be allowing configuring roles, which also define the order (inspired by how https://mobti.me allows do configure the order). This might also be a solution to #73 via configuring "Next" as an explicit role.

[haraldreingruber]

Just saw that this is a duplicate of #64