Add more Nav natives

[KitRifty]

Fixes:

• Fixed CNavArea.SetCostSoFar not being registered to natives
• Fixed CNavArea.GetSizeX/Y not defined in includes

Additions:

• TheNavMesh.BuildPath
• CNavArea.Get/SetTotalCost
• CNavArea.Get/SetPathLengthSoFar
• CNavArea.ComputePortal
• CNavArea.ComputeClosestPointInPortal
• CNavArea.GetClosestPointOnArea
• CNavArea.ComputeAdjacentConnectionHeightChange
• CNavArea.IsOverlappingPoint
• CNavArea.IsOverlappingArea
• CNavArea.IsOverlappingExtent
• CNavArea.GetDistanceSquaredToPoint
• CNavArea.IsEntirelyVisible
• CNavArea.IsPartiallyVisible
• CNavArea.IsPotentiallyVisible
• CNavArea.IsCompletelyVisible

One thing I'm not sure of is handling SMPathCost. Since this exposes NavAreaBuildPath as the TheNavMesh.BuildPath native, it requires a generic path cost function, but NavPathCostFunctor typeset has a INextBot argument. I figured that to ensure backwards compatibility, I kept the typeset the same, and in BuildPath's SMPathCost object, I pass nullptr as the INextBot argument. Added PathFollowerCostFunctor.

Tested and working on Windows.

[Kenzzer]

Good job on exposing the rest of the natives. As for the problem you raise regarding NavPathCostFunctor, it comes from CBaseNPC early days, when extension used to be a very small library, only focused on exposing pathfollower to its plugin.

Thankfully NavPathCostFunctor is a typeset, and there shouldn't be many projects out there making use of it. It should be safe to rename NavPathCostFunctor to PathFollowerNavPathCostFunctor, without breaking backwards compatibility, and make a new NavPathCostFunctor without INextBot param.

[KitRifty]

I’ll try that then, thanks. PathFollowerNavPathCostFunctor seems like a mouthful, though. Would PathFollowerCostFunctor be sufficient instead?