[ADD] added commands !add to add/join telegram user/chat and !del to leave/delete it
[FIX] fixed behaviour that transport contacts shown offline if using more than 1 priority
[SVN] bump to version 2.0
[UPD] now transport working with telethon 0.15.5 and sleekxmpp 1.3.2
[FIX] fixed everlasting authorization requests. if you got deauth message — ignore it, FROM subscription is enough.
[ADD] implemented roster exchange via XEP-0144
[ADD] we will send authorization request when unknown contact sent us a message
[ADD] correct presence handling for transport and users
[ADD] fixed presence spam (by default, we updating presence once for 60 seconds -- look at `status_update_interval` in mtproto.py)
[ADD] we will automatically connect to all actual sessions after transport start
