Add Yes/No to all to Conflicting relation dialog

[avarab@…]

I was experimenting with the data for a whole country and ended up with hundreds of "Conflicting relation" dialogs asking me whether I wanted to remove some relation from some way.

The deletion command should check for this and say how many objects it's going to be whining about and give you a yes/no to all option.

(filing this as a defect because JOSM popping up hundreds of near-identical dialogs is a bug)