lighweight highway merging rules

[kianzarrin]

fixes #1530 . see issue for details.

ATTENTION: Only applies to highway on-ramps(merging) where lane arithmetic works (incoming= outgoing).

bonus: I also modified optimized the way global options variables are accessed. to speed up value access I cache the delegate. this reduces one if condition to check null.

latest branch build: TMPE.zip

tests:

• [x] routing: cars will stay in lane when condition is met. this can be tested using routing detector tool.
• [x] edit option: changing option takes effect immediately.
• [x] no more than one highway rules policy: enabling legacy highway rules or the new highway merging rules disables the other. it should be possible to turn both off.
• [x] option persistency: highway rule option should persist when saving/loading game
• [x] routing persistency: when saving with this option, existing highways will keep their routing after load.
• [x] main menu: it should not be possible to change this option in main menu.

test condition: according to #1530.

• [x] only works on highways. Does not work on urbran/transition nodes.
• [x] only works when merging
• [x] only works when lane mathematics add up (ie incoming lanes == outgoing lanes).
• [x] only works when there is no lane connections on the merging lanes. (same as legacy)
• [x] there is no cars may switch lanes on junctions rule. (same as legacy)
• [x] does not restrict lane arrow tool.

backward compatibility:

• [x] legacy highway rules still works
• [x] legacy routing persistency
• [x] legacy option takes effect immediately.

[krzychu124]

Werid behavior:

• initial state: both options disabled
• enabling highway rules (old) and then enabling highway rules (new) disables both and also calls OptionsManager.UpdateRoutingManager() 3 times.

[krzychu124]

@kianzarrin did you test this? After reading the code I doubt it does anything when "new highway rules" is enabled and may apply changes to non-highway roads too if somehow works.

[kianzarrin]

@krzychu124 its draft. did you read description?

[krzychu124]

It wasn't a draft when I was reviewing and testing the code...

[kianzarrin]

I did not ask for review on this on the description said this is not ready.

[kianzarrin]

@krzychu124 did you test this? After reading the code I doubt it does anything when "new highway rules" is enabled and may apply changes to non-highway roads too if somehow works. I don't understand why you say that. Except for a typo the code is otherwise fine:

and does not apply to non-highway either.

[kianzarrin]

@aubergine10 @krzychu124 I hope you didn't forget about this. I have addressed the issues you raised.

[kianzarrin]

@aubergine10 have your concerns been addressed?

[originalfoo]

@kianzarrin I'll be testing this later today.

[kianzarrin]

@aubergine10 can I merge this? (you have requested changes).