- Fee tx status is now tracked using a dedicated field, with values none/received/broadcast/confirmed/error.
- Fee tx hex and hash are now both set in /payfee. The absense of txhash is no longer used to determine if a fee tx has been broadcast or not.
- setvotechoices can no longer be called before a fee is received.
- Remove `binding:required` from response types. It has no effect on responses, it is only needed on request types which are validated by gin.
* Delay fee broadcast and adding tickets to wallets.
- Adds a `background` package which implements a dcrd notification handler. On each blockconnected notification, tickets with 6+ confirmations are marked confirmed, relevant fee transactions are broadcast, and any fees with 6+ confirmations have their tickets added to voting wallets.
- VSP fee is now an absolute value measured in DCR rather than a percentage. This simplifies the code and is more appropriate for an MVP. We can re-add percentage based fees later.
- Database code for tickets is now simplified to just "Insert/Update", rather than having functions for updating particular fields.
- Pay fee response no longer includes the fee tx hash, because we dont necessarily broadcast the fee tx straight away.
* Const for required confs
