NIP-118, Polls on Nostr

[abh3po]

This NIP takes the ideas evolved from

• https://github.com/nostr-protocol/nips/pull/1190
• https://github.com/nostr-protocol/nips/pull/1324
• https://github.com/vitorpamplona/amethyst/issues/935
• https://github.com/nostr-protocol/nips/pull/320
• https://github.com/nostr-protocol/nips/pull/148

and tries to combine them in a spec for a simple polls implementation.

Working version: https://pollerama.fun/

cc: @staab @vitorpamplona @vicariousdrama @alexgleason @gocedoko @fiatjaf