Expose a line of sight method to the Grid class

[Yonaba]

Will check if a given node is visible from another given node.

-- Returns true if nodeB is visible from nodeA or vice versa
-- allowDiagonal will depend on the number of allowed directions when moving.
function Grid:lineOfSight(nodeA, nodeB)

[Yonaba]

I will definitely have to try Eugen Dedu's Bresenham-based supercover line algorithm for the following reason:

[Yonaba]

There is an implementation available.

[Yonaba]

The following paper can also serve as reference: A fast voxel traversal algorithm for raytracing (direct pdf link)