[doc] Major compatibility notice
[major] Making compatible with Primus 2.x.x
[minor] Adding back reserved events
[minor] Point to primus-multiplex master branch
[minor] Point to primus-multiplex master branch
[release] 3.0.0
[minor] package.json update
[minor] Fixing some comments and avoiding the use of `__proto__`
[codestyle] Applying minor adjustments
[test] Adding test for `primus-rooms` reserved events