Make kind 7 act as parameterized repleaceable event

[arthurfranca]

Considering NIP-25 is marked as a draft, thought of a way of fixing some problems with the reactions while not breaking current clients. Although the possible values of the d tag may look unusual, it is just specific to kind 7.

This should make it possible to:

• react to all kinds of events (but ephemeral) or to a pubkey (profile)
• react once to save relay disk space
• allow edits to content
• re-use relays existing parameterized repleaceable event handling logic to do edits
• request just the reactions to an event (using { "kinds": [7], "#d": ["note id"] } filter), instead of including all thread reactions

I think it would be better to also suggest to include just 2 tags, the d tag (required) and only one p so that the owner of the reacted to post/profile can be notified, instead of everybody in the thread, while also saving space. But i didn't add it to not make current clients mad.