MPR-704 SteamMatchmaking - creating, retrieving, listing, joining and leaving lobbies.

[javasteam-bot]

A new PR was merged over at SteamKit. It should be checked if it's relevant for JavaSteam or not.

Merged at 2019-08-16T02:01:58Z
Head over to the PRs to see more details. (no direct links to avoid reference spamming).