Added quorum_lookup

quorum_lookup picks lookup_result_enties by following rules:
1. If there are quorum lookup_result_enties with the same
timestamp, they are the final result
2. Otherwise the final result is lookup_result_enties with
the greatest timestamp
Added parallel_lookup

It lookups an information for the key in parallel in all groups
You should use it in case of you need lookup_result_entry from
more than one group
This method allows you to get lookup_result_entries almost
simultaneously from all replicas
In fact time of work almost equals to time of the slowest group
Opposite time of work of a series of lookups equals to amount
of time of work of each lookup
Fixed code style
Reimplemented prepare_latest, parallel_lookup and  quorum_lookup

Now all this lookups have common base
Added tests for parallel_lookup and quorum_lookup
Uses checker in parallel_lookup_impl to be able to check reply_error
Added comments for tests
Merge pull request #499 from shaitan/master

Combined old and new functionality of elliptics.Node.add_remote. Added tests for elliptics.Node
dnet_add_state: return positive number of added states or negative error value. Added comments about this function.
Merge branch 'master' of github.com:reverbrain/elliptics
v2.25.6.7
Set total_count of handler for correct work of session's checkers

Also quorum_lookup doesn't set a reply_error, the reason is:
- it's possible to get good responses from the quorum of groups and
  errors from the others and it's not an error in general for quorum_lookup
- it's possible to get only a good result from a group and errors from
  others and it's also not an error for quorum_lookup
If user want to distinguish these cases, he can set a corresponding
checker for session
Fixed test_quorum_lookup and added several tests:

test_partial_quorum_lookup
test_fail_partial_quorum_lookup
test_fail_parallel_lookup
test_fail_quorum_lookup
Merge pull request #495 from iderikon/master

Added quorum_lookup
Tests: fixed test_lookup_non_existing.
state: when searching state using address, do not print error if it was not found
Merge branch 'master' of github.com:reverbrain/elliptics
ioserv.conf: fixed flags description typo
v2.25.6.8
routes: do not add too many route check addresses

It is possible that under certain conditions route check addresses
will contain all nodes from the route table. This means every
check timeout all nodes will be asked for its route table.

This can lead to slowing down client which has to receive and process
all route replies.