added `exit_reason::as_string`
fixed possible bug in sync messaging

this patch fixes a possible bug caused by uninitialized variables
better diagnostic in unit tests

this patch fixes the ordering of expected/found in the
output and prints booleans properly
added shutdown handshake to test_remote_actor

the added shutdown handshake fixes a possible unit test failure
(remote actor calls `shutdown` before final message was sent)
added `skip_message` utility function

this utility function allows users to skip messages manually
improved message_future API

this patch allows to pass any number of functors to `then`/`await` and
moves `receive_response` and `handle_response` functions to message_future.hpp
fixed handling of 'TIMEOUT' messages
set `util::conjunction<>::value == false`

this patch changes `conjunction` to evaluate to false if given
template parameter pack is empty
harmonized output of unit tests
improved unit test for sync send

this patch adds tests for functor-only usage
changed version to 0.6
manual update
bugfix for `detail::behavior_stack` + maintenance

this patch fixes an issue in `behavior_stack`: in case handlers are
invoked from cache, the behavior is not copied beforehand
use `util::comparable` for message_id_t
Merge branch 'unstable' into topic/opencl

Conflicts:
	cppa.files