[Epic] UI: Lights Tool

[originalfoo]

This is a redux of VictorPhilipp/Cities-Skylines-Traffic-Manager-President-Edition#143

Requires #3 and #4

When customising traffic light sequence, I think it would be much more intuitive if the visualisation was on the roads, rather than floating panels.

Each lane connection (either as customised by user or default routing, as applicable per incoming lane) would be illustrated on junction as a thin white or grey line, also showing conflict points when zoomed in (see #4).

For each incoming lane, a small circle at the junction-end of that lane depicts the traffic light state for that lane in the current step:

• Grey circle outline = none of the steps in the sequence currently have a 'green light' for this lane
  • Solves Show notification if one specific traffic light of a timed light never changes to green VictorPhilipp/Cities-Skylines-Traffic-Manager-President-Edition#36
• Red circle outline = red light
• Green filled circle = green light

This approach fixes VictorPhilipp/Cities-Skylines-Traffic-Manager-President-Edition#90

Clicking the circle:

• Left click (primary button) toggles between green/red
• Right click (secondary button) clears any green lights for this lane within the entire sequence (ie. circle goes grey)

When an incoming lane has the green filled circle (ie. green light for current step), additional visualisation occurs:

1. The 'lane connectors' applicable to that lane turn green (normal width)
2. The incoming lane is given a green outline (similar to how old Traffic++ mod outlined lanes) all the way back to the previous junction node (or end of network)
3. The outgoing lanes connected to the 'green lit' incoming lane get orange outlines all the way to the next junction node (or end of network)

Note: Visualisation for 2 and 3 above would probably need a segment count limit (eg. if the traffic lights are on a highway junction that trails all the way to the edge of the map; rare but not unheard of).

This would make it massively easier to see what's going on, because it clearly depicts the lane the traffic arrives from, the route across the junction (including conflict points if applicable - see #4), and the lanes the traffic will exit on up to and including the next junctions (hugely useful when sequencing multiple junctions). Also, the presence of any grey circles alerts me to lanes that aren't getting any 'green time' in the entire sequence.

If possible, also allow the pedestrian crossing to work in similar way - ie. circles at both sides of road, and even on median if possible (I saw discussion on Steam with user asking if it's possible to make pedestrians wait at the median before completing journey across the road). The pedestrian crossing could also indicate conflict points (eg. cims crossing a lane that's on green light = bad).

[originalfoo]

Source repo for old T++ mod: https://github.com/joaofarias/csl-traffic

[originalfoo]

In the UI panel that lists the steps, hovering over an existing step could quickly show the UI on the roads (eg. the green lane highlights and so on) allowing user to quickly see how the sequence works.

[originalfoo]

As this new UI would be lane based, it would probably merit a keyboard modifier to allow toggling all lanes on one direction (for a given segment):

• Click: toggle light state of clicked lane
• Right click (secondary mouse button): clear all light changes for clicked lane (i.e. set to grey circle)
• Shift+Click: toggle light state for all lanes on current segment that travel in direction of clicked lane
• Shift+RightClick: like shift+click, but clears all light changes (ie. grey circles them) for affected lanes