Fix calculation of balances and available coins.
Fix calculation of balances and available coins.

No longer consider coins which aren't in our mempool.

Add test for regression in abandonconflict.py

PIVX-Project/PIVX,PIVX-Project/PIVX,Darknet-Crypto/Darknet,PIVX-Project/PIVX,Mrs-X/Darknet,PIVX-Project/PIVX,Mrs-X/PIVX,Mrs-X/Darknet,PIVX-Project/PIVX,Mrs-X/Darknet,Mrs-X/PIVX,PIVX-Project/PIVX,Darknet-Crypto/Darknet,Mrs-X/PIVX,Darknet-Crypto/Darknet,Mrs-X/Darknet,PIVX-Project/PIVX,Darknet-Crypto/Darknet,PIVX-Project/PIVX,PIVX-Project/PIVX,Mrs-X/PIVX,Mrs-X/Darknet,Darknet-Crypto/Darknet,Mrs-X/PIVX,Darknet-Crypto/Darknet,Mrs-X/PIVX,Mrs-X/Darknet