added convenience constructor to `option`

a constructor call with two or more arguments is now considered to be
value initialization
added ctor to partial funs taking `match_expr`s
disambiguation for operator==(self_type,actor_ptr)
added std::function typedefs for convenience
don't use groups in philosophers example

this patch removes spawn_in_group from the dining philosophers example
to keep the example more focused and simple
rewrote kirby example to use event-based actors
don't use groups in philosophers example

this patch removes spawn_in_group from the dining philosophers example
to keep the example more focused and simple
fixed bug in scheduled_actor::init

this patch allows actors to send a message to themselves in `init()`
modified all examples do use event-based API only
updated file names in project file
renamed `quit_actor` to `send_exit`
added `local_actor::has_sync_failure_handler`
added `gval` (enforces lazy evaluation)
use sync_send in hello world example
Merge branch 'unstable' into topic/opencl

Conflicts:
	cppa.files