(https://blueprints.launchpad.net/tarantool/+spec/compile-with-external-luajit)

Fix a valgrind warning in sptree.h discovered by new tests.

Add a way to do nested iteration in Lua stored procedures.
Implement destruction for tree indexes and iterators.
This clears a few valgrind warnings.

A fix and a test case for
https://bugs.launchpad.net/tarantool/+bug/750658

--background neither closes nor redirects stdin/stdout/stderr

--background option didn't work properly, since stdin/stdout/
stderr streams were left open and pointing to a terminal.

This lead to a hang when tarantool was started from a
shell script or over ssh.

If --background option is given, we need to fork,
try to create a pid file, close stdin/stdout/stderr
and then initialize the logging
subsystem.

Fix a bug when Tarantool exceptions were intercepted
by Lua in lua_pcall(), and converted to Lua errors.
Let Tarantool exceptions pass freely through Lua, by using
lua_call() instead of lua_pcall().

In case of any Lua error lua_call() aborts execution of the
entire process. Register lua_atpanic that converts
lua errors to Tarantool exception ER_PROC_LUA.

Unwinding the stack in this manner didn't work properly
with libcoro 6.0, which we were using. Update
libcoro library to version 6.06 to fix this problem.

Touch the generated files at configure
to avoid unnecessary rebuild.

Fix out-of-source builds and tests (test/box/protocol.test
was the main offender).

client/tnt_bench: benchmark client
test/box/connector.c: client C library test

Tweak my previous patch for proctitle to be a bit
more robust to the path length.

Start pruning Tarantool wiki on github, and add documentation
on Tarantool process title to the user guide, since
it is present on the wiki but not in the user guide.

While at it, make the process title more lookalike on Linux
and FreeBSD, and rename some of the (what looks to me as) unclear
process titles.
The documentation reflects the new naming scheme already.

Update auto generated (by confetti) cfg/prscfg.c.

Replace fiber->reading_inbox with corresponding FIBER_READING_INBOX flag.
Replace coro_save_and_longjmp in fiber_raise with tnt_raise of tnt_FiberException.

CMAKE_C_FLAGS variable.

Implement
https://blueprints.launchpad.net/tarantool/+spec/consistent-header-guards

Audit all header files in tarantool code base for consistent use
of header guards:
- consistent naming scheme, following doc/coding-style.txt
- header guard goes before the copyright
- each header is self-sufficient.
- add copyright headers where they were missing.

Remove __packed__, __unused__, __noinline__ and __regparm2__ from util.h,
since the name __unused__ conflicted with a parameter name in
third_party/valgrind/valrgind.h, which led to a dependency in inclusion
order between util.h and this header. The define names were not standard, I
couldn't come up with some meaningful and standard names, and they were only
saving some typing, while not providing any extra functionality.

"qsort implementation fails to sort arrays greater 4GB"

Generalize CMake build scripts to be able to
easily add new modules (such as box or feeder).
Move prscfg.{h,c} (confetti general library and
header) from third_party/confetti/ to cfg/ to
simplify the build.
Update configuration file templates and parsing
code to use the new confetti.
Rename cfg/tarantool_cfg.h to cfg/warning.h,
to be able to reuse it in warning.c.
Update tests.

Note: tarantool_feeder is now built in mod/feeder;
tarantool_silverbox is built in mod/silverbox.
Modify .gitignore accordingly.

Addition of required configuration file options broke backward compatibility
(https://bugs.launchpad.net/bugs/708685)

Use the new version of confetti that allows to determine whether array element
is initialized.

Use CMake to:
- Compile tarantool_silverbox, tarantool_feeder.
- enable ./test-run testing out-of-source
- implement Debug/Release configurations
- add ENABLE_BACKTRACE ENABLE_TRACE and HAVE_BFD switches
- support auto-generated targets

Post-review fixes: realign help text to match
exactly GNU tools (21st column), reorder help
messages to provide most relvant options first,
edit help text, print values for default options.

Style edits of gopt option library:
add API comments, remove trailing spaces.