Fix problem with accepting tx to mempool.

The update to 1.0.13 introduced an issue where transactions spending unconfirmed outputs were not allowed into the mempool.  This is fixed now.  Hopefully that's all the pending problems at the moment.

Note that this is only tested "a bit" for now, so be careful - I'm going to run this on my nodes and see how it goes.  But I think it "should" be fine and it does, indeed, fix at least some potential problems.