Direct Messages and other fixes

[AlTech98]

Done:

• DMs and group DMs should work
• Fix bug with discriminator starting with 0
• Fix user's public_flags type string -> number
• Keep user's DMs closed states, fix DM channel bookkeeping #365
• Fix gateway permission check, Thanks @Flam3rboy
• Fix bug in GET /channels/#channel_id/messages/ around/before/after
• Fix READY event users
• GET /users/@me/relationships
• PUT /channels/#channel_id/recipients, fix Route: /channels/:id/recipients/:id #19
• DELETE /channels/#channel_id/recipients, fix Route: /channels/:id/recipients/:id #19
• Dummy GET /sticker-packs
• Dummy GET /sticker-packs/#id

TODO:

• Fix gateway not sending events to channels created after the websocket connection has been made
• Fix gateway keep sending events to users that left the group dm channel until they refresh the page
• Remove console.log() from gateway listener and emitEvent()
• GET /users/@me/channels
• Change owner_id in a group dm if the current owner quit
• Delete group dm channel if everyone leave
• Should guild invite list DM groups?
• DM groups icon

In util i also added service and dto layers to keep the code cleaner

[SamuelScheit]

Also can you explain what you doing with Recipient.closed?

[AlTech98]

Also can you explain what you doing with Recipient.closed?

It's needed to fix #365, if a user close a dm channel in the client we need to set it as closed to prevent sending the channel in the READY event, this way it doesn't reappear in the gui until the user reopen it by trying to send a DM to the other recipient

[AlTech98]

Everything should work now, the only problem is that the gateway doesn't properly remove listener but it does that for everything not only DMs

[SamuelScheit]

Then we can merge the PR and work on the fix in another one