Fix for issues ModuleEngineFX thrust

This is based on the fix suggested here:
http://forum.kerbalspaceprogram.com/threads/56399-DEVELOPMENT-SLOWED-RemoteTech-2?p=1175820&viewfull=1#post1175820

However this is currently completely untested
Merge pull request #2 from Jaidan/module-engine-fx-fix

Module engine fx fix