api: remove box.session.push usage

[laines-it]

Removed box.session.push() usage:
Future.AppendPush(), Future.GetIterator() methods,
ResponseIterator and TimeoutResponseIterator types,
pushes[] field in Future and related methods.
Removed tests which became unnecessary.

I didn't forget about (remove if it is not applicable):

• Tests (see documentation for a testing package)
• Changelog (see documentation for changelog format)

Closes #480

[oleg-jukovec]

Please, rebase on the master branch and re-format the commit message (update prefix and just to make it look better):

api: removed deprecated methods

Removed `box.session.push()` usage:

* `Future.AppendPush()`, `Future.GetIterator()` methods;
* `ResponseIterator` and `TimeoutResponseIterator` types;
* `pushes[]` field in `Future` and related methods.

Closes #480

Also, it would be a good idea to clean up here:

go-tarantool/config.lua

Lines 177 to 183 in 802aa24

	local function push_func(cnt)
	for i = 1, cnt do
	box.session.push(i)
	end
	return cnt
	end
	rawset(_G, 'push_func', push_func)

[oleg-jukovec]

Nit: we need to add a log message here, something like:

unexpected IPTOTO_CHUNK for request %d, box.session.push is unsupported

and a test for it.

[laines-it]

After removing Lua push_func, the IPROTO_CHUNK occurrence is no longer possible. Maybe we need to completely remove IPROTO_CHUNK mention? (furthermore, I've already written in changelog.md that I deleted it)

[oleg-jukovec]

If you add a test to the IPROTO_CHUNK log message, then you can leave the function as it will be used.

[oleg-jukovec]

IPROTO_CHUNK relates to an implementation detail that not everyone understands. It's best to make a statement like this.

A push message is expected, but not supported.

Suggested change

	log.Printf("unexpected IPROTO_CHUNK for request %d", header.RequestId)
	log.Printf("unsupported box.session.push() for request %d", header.RequestId)

[oleg-jukovec]

Please, add a test for the message if possible.