!show Title Voting Improvements

[xPMo]

Unfortunately, these aren't possible with the current Element poll.

• Better post-show poll experience:
  • Add !show poll to display the poll without ending the show
  • Send edits to the poll when new !show suggestions are received (Not allowed at this time)
  • Subsequent calls to !show poll show just the new suggestions made.
• Multi-select: Polls wishlist element-hq/element-meta#533

Edits to a poll are not permitted, but we could simply collate all the new suggestions and then !show poll again, instead of having to !show start !show end.