New features for P2P mode

[WillTDA]

I shall split this into two parts:

Allow Peer-to-Many

A system could be introduced (perhaps through a numerical input on the UI, made accessible through an environment variable flag on the server) that allows more than one peer to recieve a file from the same connection code. The UI and current P2P implementation would have to be updated to allow for this.

Transfer Sessions

A system could be introduced (perhaps through a toggle option on the UI, made accessible through an environment variable flag on the server) that allows connected peers to trade files across the same connection, instead of having to open multiple. There could be a table view for either user to offer files, and the other user can press a button to request the file. This system could also be improved with Peer-to-Many, discussed above.", allowing multiple people to trade multiple files between each other.

[WillTDA]

To allow these features to be stable, it would be worth making the switch to the well-established webtorrent protocol.
#34

[WillTDA]

Now that v3.0.0 is using an updated implementation of custom P2P protocol, it'll need to be adapted to support this feature.