monitor: removed commands history.
Merge pull request #510 from shaitan/master

monitor: removed commands history.
monitor: restored 'group' at 'backend->config'.
python: added make_readonly and make_writable to elliptics.Session
Merge pull request #511 from shaitan/master

monitor: restored 'group' at 'backend->config'.
v2.26.3.16
Python: fixed make_writable.
Merge pull request #512 from shaitan/master

Python: fixed make_writable.
v2.26.3.17
reconnect: always add address into reconnection queue until it is EEXIST, ENOMEM or EBADF error
v2.26.3.18
monitor: add 'group' to 'backend->config' only if it was requested
Pytest: added checking requesting all categories.
Merge pull request #513 from shaitan/master

monitor: added tests that requests and checks all categories. Fixed adding group to 'backend->config' for non-backend categories.
v2.26.3.19
trans: Fixed trans_id at transactions' destruction
library: Added session::request_single_cmd
Merge pull request #514 from euroelessar/master

trans fixes & session::request_single_cmd
net: Fixed debug output for route lists
server: Set not-null address for accepting state
net: Fixed parsing of route list for dual stack