Move Box API declarations to box.h.
Make box.h a public header.
Add comments to box functions.
Rename fuctions accordingly.
Make includes for connector/c more local.

are not configured in the sequential order".

Fixing bug - absence of termcap and curses headers

Move the  block with @finally into an own function.

Implements
https://blueprints.launchpad.net/tarantool/+spec/fiber-specialization

After this patch, all requests even within the same session
are handled asynchronously, and responses are sent to the client as
soon as they become ready, regardless of the request position
in the input buffer.

This also changes  the internal implementation of iproto
from a "one fiber per connection" pattern to "fiber work crew"
pattern. This approach significantly reduces the amount of
context switches between fibers.

There is a bug in gcc Objective C support and nested exception,
with which an exception passes by a @catch clause if
there are nested @finally clauses. This patch doesn't work
around this bug, so if the server is compiled with gcc and
the client closes its side of the socket without fully reading
the input, the server terminates. The server needs to be compiled
with clang for now to work around this bug.

Do not modify output buffer between yield points:
in net-split, multiple fibers work on the same
session, and append output to the same output
buffer.