Fixes for grid_check random event.

There was an issue, when APC with removed cell in area was powered at
power_restore() proc. That's was making area always powered despite APC
being broken.
Removed part of code which unpowers area directly, bypassing the APC
process code. This makes grid_check event less laggy and smooth.
Downside is lights not being shut down immediatly.
AI SMES still not being affected after this fix.
Fix for infinite loop in smokeFlow() proc.

When chemical grenade being activated on any unsimulated turf (for
example a space turf), smokeFlow() starts an infinite while loop,
overloading the server.
With the only one unsimulated turf in pending list while() loop can't
finish itself and for() loop can't start.
This fix makes chemical grenades being able to explode in space without
server overload while not affecting their current game logic.