This patch adds `src/module.h` header file with definition of all public
API functions suitable to use in Lua/C modules for Tarantool. This header
is automatically generated from src/*.h by CMake (`make generate_module_api`)
by extracting code blocks between /** \cond public */ /* \endcond public */
Doxygen-style comments.

Definitions of functions in module.h are frozen and must not be changed by
future commits/releases. A new test case `app/module_api` is added to check
compilation, linkage and loading of Lua modules and functionality of
provided API functions.

Other changes:

 * Convert mysql and pg to use module.h and prepare to convert to .c
 * Fix includes in say.h, coeio.h
 * Rename luaL_pushnumber64 to luaL_pushuint64 and
          luaL_pushinumber64 to luaL_pushint64
 * Add LUA_API macros to public luaL_* functions (actually adds extern "C")

Add _vspace, _vindex, _vuser, _vfunc and _vpriv virtual spaces (views)
which contains only objects allowed to the current user.

This patch is needed for client connectors to work under non-admin user.

~/.config/tarantool superseeds /etc/default, not augments it

Extract xlog.test.py into an own test suite, in preparation
for a split into many tests.
xlog.test.py restarts the server all the time anyway, there is
no point to keep all tests in the same file.

Deal with collateral damange of this seemingly innocuous move:

 * fix an assertion failure in user.drop(), user_has_data().
   The check was using a wrong index.
 * fix test-run.py to leave cores around in case of a server crash
   (in a friendly gesture to develoeprs, and joining the ranks of
   such extremely succefful applications as apport and systemd, it used to
   delete them)
 * update bootstrap.snap to provide format for _index space
 * make a bunch of tests safe to the order in which they are executed
 * use space name rather than space id for error messages more often,
   since space id is very volatile after introduction of max_id sequence
   for space ids.

Use a monotonically growing sequence for space identifiers,
to ensure they are never reused.

Update tests.

Update tests to use this role.

Introduce 'public' role.
Auto-grant 'public' to every user.
Update the snapshot.

0) DIST.LUA: Move dist.lua to tarantoolctl (+ DEB + RPM + DOCS)
0) DIST.LUA: Delete -w option
1) CMAKE: Add pod2man function for generating MAN Files from POD format
2) RPM: Add man files for tarantoolctl, move tarantoolctl+initscripts
from `tarantool` into `tarantool-common`
3) DEB: Remove tarantoolctl.1 creation
4) Remove trailing whitespaces

Fixes gh-570
Fixes gh-557

Recognize -w --wrapper, and don't daemonize if run from a wrapper.

 + Add tarantoolctl enter instance_name command

+ Fix logrotate.d config. #473

Don't try to execute a Lua script.

- change /etc/default format to Lua
- change defaults format to tarantool.cfg
- don't force logger/snap_dir/wal_dir/work_dir if it's set
- minor fixes in logging
- implement fio.dirname