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")

Conflicts:
	src/box/index.h

Code review fixes for sysview branch.

Accept patches from Jörg Richter which fix a bug and implement
a todo item in the small allocator, and change slab_alloc_minimal to
16, to work well out of the box with small tuples.

Add missing comma to iproto_constants.c.

Required for #194

A fix and a test case for gh-791: call() return value can't contain
a Lua map.

Treat a map as a scalar, i.e. convert it to a tuple field on return
from call.

Use a simple heuristics to distinguish a map from an array:
if the first key of the map is integer 1, it's an array.
This approach works pretty well for JSON maps, which can't have
non-string keys anyway.

If failed to set locale to C.UTF-8 (the standard one which supports UTF-8),
try other options. Keep trying ad naeuseam to silence the warning,
since this raises support questions.

CentOS 6.6 has en_US.utf8.
Debian, FreeBSD and Darwin have en_US.utf-8.

Provide a good memory footprint out of the box.

fix typo at box-protocol description

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.