If a long reorganize occurs farther back than the last saved recent
block hash (currently max 20 are saved) a full rescan is triggered
since there is no guarantee the previous blocks weren't also removed
in the reorg. In this case, the address manager was set unsynced, but
transaction history was not rolled back as well. This commit corrects
this by unconfirming all transactions but those in the genesis block.
This a refactor of the btcwallet main package to create a new wallet
package.
The main feature of this package is the integration of all the other
wallet components (waddrmgr, txstore, and chain) and the Wallet type is
'runnable', so it will be continuously updating itself against changes
notified by the remote btcd instance.
It also includes several methods which provide access to information
necessary to run a wallet RPC server.
