job: add doc
all: new job.New API
core: doc-strings
app: doc-strings
base: doc-strings
core, ctx: Context.Id() -> .ID()
app: fsm_XYZ -> fsmXYZ (golint)
all: Context.Id() -> .ID()
dflow: elem_t -> elemT (golint)
error: doc-strings
inputstream: doc-strings
outputstream: doc-strings
io: doc-strings
test: honor OutputStreamer doc
msgstream: doc-strings
registry: doc-strings
registry: more doc-strings
registry: golint
registry: golint
worker: golint