v0.7.0

This release adds no major new features. Instead, a number of refactors were done in dependencies as well as the main library. Actor execution latency may be somewhat faster now because of an upgraded dependency on waPC.

All global static variables have been removed and are now private fields on the WasccHost struct. In addition to being cleaner code, this may reduce friction for those trying to write concurrent integration tests against WasccHost.

The only breaking change is the Actor::from_gantry method has been removed. Actors should be freestanding instances that don't require the use of the gantry feature. Now, there is an add_actor_from_gantry method on WasccHost that replaces the old function (if the gantry feature is enabled).