Respend transactions that conflict with transactions already in the
wallet are added to it. They are not displayed unless they also involve
the wallet, or get into a block. If they do not involve the wallet,
they continue not to affect balance.
Transactions that involve the wallet, and have conflicting non-equivalent
transactions, are highlighted in red. When the conflict first occurs, a
modal dialog is thrown.
CWallet::SyncMetaData is changed to sync only to equivalent transactions.
When a conflict is added to the wallet, counter nConflictsReceived is
incremented. This acts like a change in active block height for the
purpose of triggering UI updates.