Server send timeouts extension

[bioothod]

Currently neither copy/move iterator nor server-send operation allow setting write command timeout, which is vital for long-distance connections and slow links between groups. This pull request allows to set this parameter from command line options already present in all clients (python and C++ bindings).

This pull request breaks backward compatibility for server-send command, but since our internal tools are the only users of this feature, it should be ok.

[shaitan]

Build has been failed on server-send tests:

[16:09:19][Step 1/3] Set base directory: "/tmp/buildd/elliptics-2.26.10.3/obj-x86_64-linux-gnu/tests/result/dnet_server_send_test"
[16:09:19][Step 1/3] Set cocaine run directory: "/tmp/elliptics-test-run-384e9457/"
[16:09:19][Step 1/3] Starting 3 servers
[16:09:19][Step 1/3] Starting server #1
[16:09:19][Step 1/3] Started server #1
[16:09:19][Step 1/3] Starting server #2
[16:09:19][Step 1/3] Started server #2
[16:09:19][Step 1/3] Starting server #3
[16:09:19][Step 1/3] Started server #3
[16:09:20][Step 1/3] Started servers
[16:12:59][Step 1/3] Running 24 test cases...
[16:12:59][Step 1/3] /tmp/buildd/elliptics-2.26.10.3/tests/server_send.cpp(253): fatal error in "(ssend_test_server_send, src_noexception, 1, id_prefix, data_prefix, delayed_groups, iflags, -110)": critical check it->reply()->status == status failed [0 != -110]
[16:12:59][Step 1/3] 
[16:12:59][Step 1/3] *** 1 failure detected in test suite "Master Test Suite"

[bioothod]

It is not related to this pull request, since by default it doesn't change any timeout, but uses what was set in the node or session.

[shaitan]

Current master has been built without such error:

[16:50:55][Step 1/3] Set base directory: "/tmp/buildd/elliptics-2.26.10.3/obj-x86_64-linux-gnu/tests/result/dnet_server_send_test"
[16:50:55][Step 1/3] Set cocaine run directory: "/tmp/elliptics-test-run-6d07589e/"
[16:50:55][Step 1/3] Starting 3 servers
[16:50:55][Step 1/3] Starting server #1
[16:50:55][Step 1/3] Started server #1
[16:50:55][Step 1/3] Starting server #2
[16:50:55][Step 1/3] Started server #2
[16:50:55][Step 1/3] Starting server #3
[16:50:55][Step 1/3] Started server #3
[16:50:57][Step 1/3] Started servers
[16:54:35][Step 1/3] Running 24 test cases...
[16:54:35][Step 1/3] 
[16:54:35][Step 1/3] *** No errors detected

[shaitan]

I've rebuilt 3 times master with these changes merged and it always failed server-send test.

[bioothod]

Yup, my fault, long test waits for default 60 seconds, while session used in the test has 120 seconds timeout which is now propagated into the iterator and server_send call. I've updated test with the new commit.

[shaitan]

Looks good, thank you!