[Feature Suggestion] Use a dedicated button to move layers

[lbusett]

As reported also in r-spatial/mapedit#86 (comment),
when in editing mode on polygons clicking nearby but not really "over" a vertex and then moving the mouse (or trying to pan on the map by clicking and dragging to move to another area) can lead to moving the whole polygon "by mistake".
I think therefore that it would be better if the "move whole polygon" functionality could be implemented using a "dedicated" button. As an alternative, it could be implemented by allowing to move the whole polygon only by clicking on its centroid, as implemented here (for leaflet.draw) for rectangles and circles.

[codeofsumit]

marked as a feature request. I will leave it open, no upvotes needed. Will definitely implement this.