Drowning #651

This system makes the character have a time limit for how long they can stay underwater without being hurt.  When the character gets to some air, they will regain their breath over a period of time.

Note:
The calculation of whether the character's head was above a wave was not working well.  You could stand in 2 blocks deep of water and still be breathing.
Moving this system to its own module will need to wait till NUI is complete.

Quirks:
If you snuggle up to a wall underwater, the movement system says the character is in the adjacent block and starts "breathing" because they are no longer in a unbreathable block.  Some advice on how to address this would be helpful.