quick fix for lane connector

pressing CTRL+S activates stay in lane feature. we can expand it to support the following situations:

Sometimes people use lane connector to handle split road like this: But i think that is unnecessary because changing lane arrows would be sufficient(already possible by priority tool -> CTRL+ckick): Cars are not going to change lanes if switch lane while going straight in junctions is turned off. maybe its worth supporting this too because customer is always right?

We need to limit the scope of this review so that it does not get into an all or nothing scenario. The following junction does not support quick fix: I cannot think of other junctions right now. but its worth discussing them for the second phase of this issue.

[pcfantasy]

Aha, nice to see TMPE team also want to implement this function.

actually, I have implement this function for CSUR road.

https://github.com/citiesskylines-csur/CSURToolBox/blob/master/UI/StayInLaneUI.cs AddLaneConnectionForCSUR

All outgoing lane will connect to nearest incoming lane, and All incoming lane will connect to nearest outgoing lane.

This is a quick way for Y juction in CSUR road.

Nice to see if more complex cases can by handle by TMPE tools.

[kianzarrin]

The second phase of this issue can connect the lanes from the other side of the T junction as well. Also support for 4 way junctions.

This way we can have a 4-state quick-setup state machine. StayInLane would be special case of Quick-setup where the connecting road has 0 lanes.