Fixes #1946

Fixes #1896

Pass LDFLAGS flags properly to fix packaging on Debian Stretch/Sid.

Fixes #1935

See #1939

A hotfix for #1940

* Fix buggy math calculation and simplifies randomization logic
  introduced by gh-732. The primary difference is that the new
  implementation uses fixed periods (=box.cfg.snapshot_period)
  shifted by a random offset instead of floating periods
  (=box.cfg.snapshot_period + random). In addition, snapshot daemon
  now never start snapshoting earlier than box.cfg.snapshot_period time.

* Use fiber.channel() to control daemon

Fixes #1912
See also #732

Fixes #1929

This patch doesn't introduce any semantic or functional changes.

 * :close() didn't stop reconnect activity;
 * cancelling a fiber in the ceratin request stage leads to
   deadlock in subsequent :close().

errno returned via errorno member, not in result

fio_filename replace errno by readlink call and can
be used for error logging

Allow to specify allocator context in matras and matras-based data
structures. After this change, the following salad data structures can
be passed a custom allocator context: light, rtree, bps_tree.

Conflicts:
	debian/changelog
	debian/control
	src/lib/small

diag_set(ClientError, ...) is needed for net.box and box.error()
which should work without box.cfg{}

Fixes #1814

Fix rb psearch/nsearch methods for partial key

Automatically kill all servers after the crash.

Ancient Red Hell 6 doesn't support Recommends.

Fix compilation warnings

Use strong dependency on `netbase` for Debian and weak dependencies on
/etc/protocols and /etc/services files for RPM.

Thanks to Ivan Kosenko

Closes #1794

Thanks Alexey Antipovsky

Closes #1448

Closes #1657

Regression by d36ba279

Update test run (fixes the sporadic console handshake bug when running
tests).

Fixes gh-1163.