Use vclock_sum() from WAL writer as a transaction signature.
Fix handling of transactions without the write requests.

Start network port listener only after recovering all existing at
the start xlogs.

box.cfg{} should not complain if an immutable parameter is passed again
unchanged

Add exception methods to plain C.
Add an error factory to raise exceptions from plain C.

Conflicts:
	third_party/libev/ev.c

Requested by customer.

External unwind code doesn't exists for non-x86 platforms.
Allow LuaJIT to be compiled somehow.

https://github.com/rtsisyk/msgpuck/issues/2

Building Documentation topic for issue #804

A 'tentative definition' in C language is a global variable definition
missing both a storage class and an initializer, ex: int foo.
Traditionally it get's translated into a common symbol, allowing for
multiple definitions in different translation units to coexist.

Normally multiple definitions aren't allowed; unless they are common
symbols.  In the later case a linker picks one arbitrarily.

-fno-common alters tentative definitions translation, resulting in
a more strict and conformant semantics, multiple definitions are no
longer allowed.

This change was motivated by the OSX linker not handling common symbols
in static libraries
(https://stackoverflow.com/questions/19398742/os-x-linker-unable-to-find-symbols-from-a-c-file-which-only-contains-variables)

Add members to struct error
Avoid unnecessary type conversions.

Avoid throwing exceptions from most fiber functions.

say.cc -> say.c

object.h was an Objective C legacy providing nothing, mostly, and with some
changes to class hierarchies I have in mind using it will introduce multiple
inheritance, which I'd rather avoid.