Refactor _Advanced Directions_

[koebi]

• [x] fix blue lines (#120)
• [x] don't remove vertex markers once route is generated
• [x] add option to export list to layer
• [x] make waypoints re-orderable
• [x] make waypoints drag-and-droppable
• [x] #211

[merydian]

When should the vertex markers be removed? Maybe we should add a button for it and remove them automatically when the green plus button is pressed to add new vertices?

[merydian]

For the export of the vertices i'd suggest something like this:

[merydian]

@koebi, is don't remove vertex markers once route is generated really necessary, when there an option to save the vertices as a layer?

[koebi]

Maybe we could add a hint above the choose export path that notes that the markers will vanish if not saved?

[koebi]

I've converted the one idea that was in here to a separate issue (#211) and will see this as complete :)