Fixed remove_on_fail implementation

We need to clone session to be sure that the session will be used only
in one transaction simultaneously
addr: new thread-safe helpers to print address strings
addr: use getnameinfo() to properly determine family and automatically dereference sockaddr
session: get rid of handmade address-to-string conversion, use dnet_addr_string() and friends helpers
Merge pull request #555 from iderikon/master

Fixed remove_on_fail implementation
v2.26.3.31
Merge pull request #557 from shaitan/master

Reset state if dnet_idc_update_backend has been failed.
v2.26.3.32