Give firefighting foam tanks more fuel

[kyle2143]

Firefighting foam tanks are pretty weird. They hold 1000u of foam. But each time a fire extinguisher refills from them, they lose 75u of the foam. Regardless of whether the extinguisher is empty or has only sprayed once.

You can use up a tank pretty fast without realizing it this way and it's really the only option for firefightinrs to get more foam.

Edit: Also, you still get the "refilled exinguisher" chat message and sound when you attempt to fill an extinguisher from an empty foam tank. That's kinda a bug.