prepare for better worker startup logic
log the complete stack trace in DontPanic
keep track whether worker is alive
almost able to restart workers, but semantics not quite right
cleanup
about to change channel init
channels now set up after their max capacities are known
restartable workers now ok, transformer is no longer looping
there may be a race condition, test -v sometimes hangs?
simplify
run worker while it has pending input data

fixes non-loopers with pending inbox data
still very occasional hangs in rfdata_test