Automatically adding step problem

[Roberto Braga]

At each drag and drop, a step is automatically added
Also when you edit a guide, a new step is added automatically when opening

The problem is that when you save, an empty step is saved and it is not possible to remove it (see also #4)

This can be solved in 2 ways (or both at same time)

1. discard empty steps at save time
2. add a steps delete option