* Ensure purchase height set for confirmed tickets.
* Show purchase height in admin screen.
Only show purchase height when the ticket is confirmed, because if a ticket is not confirmed, its purchase height is not yet known.
- Use bootstrap to improve layout.
- Add warning banners for webserver debug mode and vspd closed.
Admin page:
- Replace listing of all tickets with form to search by ticket hash
- 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.
