Splitting function behavior should be changed

[Bürste]

1.
If you select only one node and press C and two ways sharing this node on the mid a message should be displayed if the user really want to split all ways, but it should not infantilize the user that he can't split up more than one way at a time by only selecting a node.

2.
If you had selected many ways and one of them containing the only selected node the way which contains the node should be splitted if you press C after a question if the user really want to split up the way.

This often happens if you create bus routes, you select some ways, append them to the relation and so on. If you select a way and you see it's to long and you want to split it up this don't work as long as you still got other ways selected.