Support more than 4 attachments

[ledlamp]

Pitch

Allow more than four attachments on a post

Motivation

Since this fork adds reactions, and all the other platforms that have reactions also support more than 4 attachments, I think this fork ought to support it as well.

I like the design of mastodon but don't like it's limitations, so it's nice that there are forks like glitch-soc and chuckya to restore useful functionality and feature parity, but this one thing was a deal-breaker for me.

I think it is an especially important feature because people on pleroma and misskey frequently attach more than 4 files, and mastodon users have no clue about it.