Ray-cast functions

[eliasku]

Add function to ray-cast ray/line versus the world (walls and objects).

Unblocks different nice features:

• Railgun and ray-cast weapons, like lasers
• AI visibility
• Generate lightning

[eliasku]

Optimize raycasting for tilemap and loose grid objects

[eliasku]

• ray traversal on tilemap still need to traverse loose grids