Removed event queue freeze when power lost.

Events in the flight computer queue will continue counting down, even if the ship does not have power. If there is no power when the event is scheduled to occur, it will be ignored and an error message will be shown to the player.

Fixes RemoteTechnologiesGroup/RemoteTech#41.
Merge pull request #186 from Starstrider42/warpbug

Removed event queue freeze when power lost.