Quick setup Priority road - phase 2

[kianzarrin]

This is phase 2 for #541. also see #542 #557

Features to consider :

• high priority overlay (mass edit overlay) to show traffic lights/uturns.
• No uturns on main or yield roads.
• Support for transitional (2 segment) nodes. (remove traffic lights, no uturns, no pedestrian crossings, enter blocked junction)
• use of lane connector(quick fix for lane connector #703) . this should be much less aggressive that quick fix for lane connector #703. Only simple cases that we are sure its useful. I think its best to do it only in the scenario shown in the screenshot above
• Support lane arrows when high priority road/roundabout turns.
• Add guide/tutorial to warn about the need for collector road.
• medium priority road quick setup of meduim prioirty road  #712
• (already taken care of in (more roundabout quick setup features #863)) Undo/Clear for high priory roads (Undo/delete feature #568). This could be done in form of state machines with two states or having a clear button(GUI pannel for prioirty signs #711) or hotkey (CTRL(+SHIFT)+DELETE]

Also I was wondering is there any point to include vehicle restriction, parking or speed limit?