Visible representation of pick*() in debug mode.

I've been using the "pick" functions more often lately. For pathfinding, I'm currently calculating/rerouting players though an iteration of nodes and using pickline to check whether the path is viable or not. What would be helpful for logic/AI debugging is to have a debug flag to give a visual representation of the line/area/arc/etc. that is being picked.

It's low priority, but would be a little helpful tool to make sure game objects are really performing how we think we programmed them to.