#438 Speedlimit refactor

[kvakvs]

Fixes #438 - by Victor

• Move all constants (The decision should be based on where the constant is used)
  • either to SpeedLimitManager
  • or to a UI related class (SpeedLimitsTool?)
• Move methods EnumerateSpeedLimits, ToMphPreciseString, ToKmphPreciseString, ToMphRounded, ToMphPrecise, ToKmphPrecise, ToKmphRounded, GetPrevious, GetNext, GetVerticalTextureScale to a UI related class (SpeedLimitsTool?)
• Move NearlyEqual and IsZero to a (new?) utility class, e.g. FloatUtils
• Move IsValidRange to SpeedLimitManager
• Modify VehicleBehaviorManager.FindBestLane() such that the variable optImprovementSpeed stores velocitiy in game units (and not in km/h).
• Modify member variables MinMinSafeSpeedImprovement and MaxMinSafeSpeedImprovement in DynamicLaneSelection such that they hold velocities in game units (and not in km/h).
• If required, add two members velocity (float) and unit (SpeedUnit) to the SpeedLimit struct and update UI code to use it properly (as a composite value). If not required, remove the struct entirely.

Introduces new struct SpeedValue which contains game speed float, and can do conversions with Velocity magnitudes (8x the game speed) and Mph / Kmph. It can potentially replace float everywhere in the game logic but it spreads like a plague, once you replace something, the compiler will complain until everything became the new data type. Worth only if there is no performance loss, and i am not sure about Mono 2.0.

[kvakvs]

@dymanoid i hope [Serializable] is not adding any extra data fields to the struct. It is not used now, but may be used later if we replace more floats with this struct.
Also: I'm worried how bad is Mono 2.0 perf penalty on a struct with a float.

[dymanoid]

You only need the [Serializable] attribute if you want to use BinaryFormatter for serialization (I suppose that is not the case in TM:PE, but I'm not sure). For all other serialization types (including XML), you don't need this. It won't change the struct footprint though, so there is no harm in having it applied.

A struct with a single float should be as fast as a single float. If you are concerned about the performance in Mono, just benchmark it (using BenchmarkDotNet).

[originalfoo]

Tested in game last night and everything seemed to be working fine.

LGTM! 👍

[krzychu124]

LGTM 👍

[krzychu124]

LGTM 👍