Ducted Fan: Hover throttle, stack node, fix rotation.

Since you seem to have implemented the model rotation I had done in .cfg in the .mu, I removed it from the .cfg or we're back to the up/down thrust on mirrored parts.

Upped connection strength to decrease the effect of KSP bug 290.

Added a stack node so it can be attached to directly to the end of trusses and i-beams.

Added Firespitter hover throttle.