Make vertex markers on map drag and droppable

[merydian]

Vertices on the map can now be dragged and dropped, a live preview is also provided.

[merydian]

Should we add the option to toggle the live preview mode? Would lower the amount of requests.

[merydian]

Integrate option to use custom provider with this.

[koebi]

Hey,
I played around with this a bit, and it's definitely going into a great direction.

My main issue is, however, that there is no indication that points can be dragged - no "edit"-like button, and no change of mouse pointer when hovering over the map.

There were a few minor issues:

1. Dragging points isn't very visual - the new point only shows up when I release the mouse button.
2. Dragged points show up as new numbers in the list - > list says 1, 2, 3, 1, 2, 3, 4, 5, 6
3. Dragged points seem to get duplicated?
4. Trying to mark multiple points for deletion via shift-click (as you do in other GUIs) leads to QGIS crashing after some time :(

[koebi]

Should we add the option to toggle the live preview mode? Would lower the amount of requests.

I would even suggest making this the default. It's quite confusing that routes get auto-generated if you're not ready for it ;)