Segment ends should contain nodeId

[originalfoo]

We've got loads of excess lines of code due to determining StartNode practically every time we interact with segment ends.

That's almost always determined by segmentId.ToSegment().IsStartnode(nodeId) - so this line is appearing over and over and over again.

If we stored nodeId in segment ends, and had constructor that takes segmentId, nodeId and works out the StartNode from that, we could trim lots of code bloat (at the expense of adding a ushort to a struct). This would remove huge numbers of ToSegment() lookups and IsStartnode() checks throughtout the codebase.

What do you think?

[krzychu124]

Not bad idea if we could ensure or assume that id or rather its connection with segment won't change (always be valid). I think we should also try to merge obsolete SegmentEnd(Traffic.Impl) with ExtSegment but they have slightly different id/index generation :/

[originalfoo]

I added the constructor that takes nodeId in a recent PR #1506; it converts to startNode and stores that - just makes code a little cleaner:

https://github.com/CitiesSkylinesMods/TMPE/pull/1506/files#diff-977b7061ebbe786496caff8a3e924dd5e61a8ca30d063a4b12e897e073ab8f8a

[krzychu124]

oh, right, missed that change🤔