Two small cleanups and the offer->ACCOUNT->offer fix

1) When pathfinding, don't output a redundant account node.
This node serves no purpose because expandPath adds the node anyway. It's just a waste of bandwidth and space.

2) Cleanup some stray formatting
Obviously-correct cleanup.

3) Fix offer->ACCOUNT->offer

CAUTION: The third change affects transaction processing and requires planning and coordination in deployment. It should probably be combined with other transaction processing changes. (tefDST_TAG_NEEDED, for example.)
Tried to read through this several times but still not getting how this works.

Isn't this condition book -> account ?  Is there another implied node after this one that's an offerbook?  An offerbook can't be the last node in a payment chain - can it?