Remove global message queue

[amutake]

If global message queue is removed, the definition of config becomes just list actor.
This is required for implementing sub-configuration (#4).

[amutake]

This is incorrect.

Actor configurations of pure actor model consist of a set of actors and a multiset (not queue) of messages that are not received by targeted actor.

configuration := set actor \cup multiset message

[amutake]

and remove local message queue because there is no need to have a local queue in each actor.

actario/src/syntax.v

Line 70 in 4def5cf

(* あと、グローバルメッセージキューの他に actor もメッセージキューを持つようにしたい。グローバルキューだけだと、先頭のメッセージの宛先のアクターがいつまでたっても仕事が終わらないとき、他のアクターはメッセージを受け取れない *)