Merge pull request #127 from shaitan/master

Skips equal keys while computing diffs. Fixed errors&warnings.
recovery: more precise stats
recovery: added posix_fadvise to sort
recovery: workaround route table re-fetch

Propper solution is on the way
Merge pull request #129 from SaveTheRbtz/master

Recovery. Merge bug workaround, improved sort speed and statistics
recovery: formatting fixes
ioclient: fixed error message formatting
misc: formatting fixes
dnet: fix DNET_FLAGS_DIRECT flag behavior

Prevously DNET_FLAGS_DIRECT only affected node until route table update
or check timeout. This commit adds direct_id to session structure and corresponding methods
set_direct_id and get_direct_id for it's manipulation. If direct_id is
set then all requests always routed to the node which is responsible for
direct_id.id range.

NB! This change breaks ABI.
recovery: merge: rollback workarounds
recovery: remove lru_cache from node and session
ioserv: removed unneeded assignments
ioserv: unblock SIGQUIT and SIGTSTP

Those two signals could be sent from keyboard so it eases development:
* TSTP (Ctrl+Z) allows putting ioserv into background.
* QUIT (Ctrl+\) allows fast and unclean shutdown.
Merge pull request #130 from SaveTheRbtz/master

Recovery, bindings, ioclient and ioserv improvements
Moved merge&split method into IteratorResult. Fixed python logs levels.