Fixes critical gas freezer bug
Adds atmos/supermatter debug messages
Powernets

Moved powernet datum definition to powernet.dm
Improved APC load balancing.
Updated SMES charging to work better with new APC/powernet code.
Supermatter balance

Attempts to rebalance SM to work with new atmos machinery. Testing with
a 2-freezer 2-canister default setup, the engine can run to 500 kW at
700 K.