Territory Manager should exclude 3 territory tile border

[elexis]

In CCmpRangeManager.cpp we have

// WARNING: CCmpPathfinder::UpdateGrid needs to be kept in sync with this
const ssize_t edgeSize = 3; // number of vertexes around the edge that will be off-world

In CCmpPathfinder.cpp we have

// Compute off-world passability
// WARNING: CCmpRangeManager::LosIsOffWorld needs to be kept in sync with this
const int edgeSize = 3 * Pathfinding::NAVCELLS_PER_TILE; // number of tiles around the edge that will be off-world

This ticket can be solved in two separate patches:

1) The magic number should become a global constant.

2) The number must be taken into account in CCmpTerritoryManager.cpp as well, so that the territory line doesn't disappear in the shroud of darkness.

(This might influence #4267)