add shared borders draw assistant

[Pontiac_CZ]

It would be very helpful if JOSM had the ability to draw a way going through nodes of another way.

Example: there is a meadow already in the OSM. Now I want to draw an adjacent field. The field will share 20 nodes with the meadow. In todays state I have to click node by node to complete the shared part of the field way and have to be very careful to not miss a node or to not create a separate one.

Proposal: click a first node of the meadow border (I will stay with my example). Then pressing a key modifier (let's say AltGr or some combination of CTRL SHIFT ALT) JOSM would enter a shared border draw assistant mode. This means that if I touch the 20th node of the same way JOSM will propose a way going through all intermediate nodes (2 - 19). If I click the node 20, the suggested way will be accepted and drawn.
This would save so much work sometimes.

[bastiK]

Closed as duplicate of #4190.