Support concurrent runtime parallel processing using collaborative delegation from Actix

[naturallymitchell]

#234 + Mun's Actix integration

~~

carllerche/kabuki#5

ActorCell has a couple of todos about how it sets up and processes its slab of tasks. Could crates like futures-state-stream and petgraph help similarly to how Scala users do modeling dependent tasks in Akka?

Chymyst/chymyst-core#154

[naturallymitchell]

much progress in b81bcc2 and poga/actix-lua#23

[naturallymitchell]

poga took out actor management in actix-lua. in actix-ullage, I believe it's good to have. but he correctly pointed out that actors can't be used for short-lived tasks (link?). scripts need to setup more robust environments than our first try at web server handling per actor.