Incorrect documentation (and probably behavior) in MagnetRegionManager

[jbphet]

I came across with while working on #162. In MagnetRegionManager.getTouchingCoil, the documentation doesn't match what the function does, and what it does relies on the order in which restricted bounds are placed into what was a private variable, which seems fragile. I'll mark the area in the code with a TODO.

This appears to be related to description, and I'm not sure who is working on that for Faraday's Law, so I'll assign to @emily-phet so that she can get it to the right person.

[jbphet]

@emily-phet says that @jessegreenberg is going to be working on description, so I'm passing this on to him.