Add Buffer state mechanism like Editor state.
Need our exec created before other bits.
Better error reporting.
Added simple actor-like system (processes/pipes).

I experimented with wrapping all services in their own processes, but the
result ended up being cumbersome and didn't pull its own weight. I'm leaving
this functionality in here, because I may decide the weight is worthwhile after
all, and because there are cases where I'd like a simple actor-like mechanism
without the modeling overhead of Scala/Akka actors with message classes and
blah blah blah.
Added Funnel mechanism for inter-process callbacks.

A Funnel allows for a type-checked API where process A knows that it can safely
send results back to process B on process B's "thread" without complexity or
risk of foot shooting.