Add priority signs alongside traffic lights, and blinking yellow lights

[BuiIdTheBuilder]

This would be great with Real Time mod, but also can be used without it aswell.
We should be able to combine priority signs with traffic lights, which would be followed when the traffic lights are flashing yellow (at night or during certain phase such as a left turn). This would greatly reduce delays, because seeing your cars wait at a red light for nothing is mildly infuriating. European countries and some places in the US have this in real life.

You should also be able to allow traffic lights to blink without priority signs, in that case priority to the right rules would apply, as is the case when you set priority to every road at a junction currently.

Since there's no blinking yellow mesh/animation for the traffic lights, you could just leave it showing steady yellow in-game, but show it flashing in TM:PE.

[originalfoo]

Regarding flashing yellow lights, there's some discussion buried in the comments on #46. If there's a state where none of the lights are lit, then potentially it would be possible to create flashing yellow lights on the props by toggling between "all unlit" and "yellow lit"? Some countries also have flashing Green, which indicates the light might soon go red (or, in British Colombia, the lights are pedestrian controlled - ie. a pedestrian crossing is present - and thus could go red when pedestrian pushes button).

Regarding dynamic signage props (not really mentioned in OP, but related) see #124. Most road assets don't contain priority signs or full range of traffic light props. I suspect a solution to dynamic props would require some sort of in-game editor that allows users to add props to road prefabs and set which flags (including custom flags using Adaptive Roads mod?) will cause the sign to appear.

Regarding road rules changing based on game time, there's a bunch of things listed under the Time-dependent features milestone.