Ai player utility

helper functions for AI: testing if an object is in line of sight (and optionally if it's enabled), if a point is clear, and if an object is within a given angular field of view (optionally specified beyond a stock 45 degrees, as well as optionally checking if the target is enabled)
If I were being picky, I'd say you could do a typemask check then a `static_cast`. It's probably not a performance issue, but still...