[Facelift] Lane Connectors now have contrast outlines

[kvakvs]

• Change color palette to distinct color set, and only allocate colors for source lanes (previously both source and target lanes got allocated a color even though target lanes did not need a color).
• Render target lanes as white circles.
• Render black outline around the lane connectors, and black outline around node circles.
• Render white outline and use brighter color of the same hue, while dragging a curve

Contributes to #523

[originalfoo]

This looks good! Is it possible to make the outlines slightly thinner?

[kvakvs]

Of course possible, there is a fixed thickness offset used (and for circles a multiplier is used).

It though behaves slightly strange, there is no clean overdraw if i render two things on top of each other, it feels like overlays are grouped by color or something (by Unity), i.e. render order of overlays seems to change.

One more thing to consider, if i zoom out, those overlays may look like they have flickering black grain borders, because the border becomes narrower than 1 pix. I have not tested this because overlays disappear when the camera zooms out.

[kvakvs]

Here's with black curve width multiplier 1.5f (was 2f * colored curve width)

[originalfoo]

LGTM 👍

[krzychu124]

👍