Fix error while loading shared libraries: libbfd-2.25-system.so: cannot
open shared object file: No such file or directory

instead of RelWithDebugInfo should be used RelWithDebInfo

see https://cmake.org/cmake/help/v3.4/variable/CMAKE_BUILD_TYPE.html

* Move <files> to tarantoolsession
    - reference/tarantool.rst
    - reference/yaml.rst
    - reference/csv.rst
    - reference/json.rst
    - reference/msgpack.rst
    - reference/app_c_lua_tutorial.rst
    - reference/net_box.rst
    - reference/box_error.rst

* Style fixes
* Tables (line numbers) in code-blocks
* Errors fixes (function headers display)
* Move 'net_box' and 'box_error' into reference, cause they aren't part
  of 'box' anymore
* Add link to box articles for reference
* Move appendecies to book/app

ddl test separated in engine and sophia specific tests
sophia_join.test moved from replication to engine suite

lua_gettable() raises a Lua error in LuaJIT on
cdata objects, so has to be invoked with a pcall()
without EXTERNAL_UNWIND

Fix a race condition in status.test