coio_writev() could modify the passed parameter in case of a
partial write.

It would corrupt struct obuf, which would pass to coio_writev()
a pointer to a vector whose iov_base pointers were later reused.

The following would happen:
- iobuf_flush() would pass obuf->iov to coio_writev
- coio_writev would advance one or two iov_base pointers
- capacity value would hence become meaningless, and a subsequent
obuf_dup() would overwrite heap memory
- we would get a memory corruption in some place very distant
from where the problem originally occurred.

The fix is to preserve iovec values in coio_writev.
This is implemented by keeping a copy of the changed iovec
and restoring the original iovec value at exit from
coio_writev.

drop some ev_watchers from fiber structure.

Conflicts:
	src/fiber.m

all functions use rlist: avoid spare foreaches

Remove dependency of admin.m from the configuration file.
Remove txn->txn_flags from recover_row().

Conflicts:
	include/fiber.h
	src/CMakeLists.txt
	src/lua/init.m
	src/replica.m

Move mod/box/ src/box. Fix broken packages.
Rename tarantool_cpack.cmake to cpack.cmake.

Change memcached, admin and iproto connection to use the
buffered IO.
Make coio_writev accept a hint about the total size.
Remove fiber iov.

Remove ugly port_add_u32, port_dup_u32.
Now there are only port methods to add a tuple.
An additional method, port_eof(), is introduced
to mark the end of a result set.

Count tuples of SELECT automatically in port_iproto,
where it is needed.

Conflicts:
	include/fiber.h
	src/fiber.m
	src/replica.m
	test/box/lua.result