app: display cpu+mem evt-loop stats
worker: less verbose
Merge pull request #30 from go-hep/dev/mem-stats

Dev/mem stats
doc: update fwk-ex-tuto-1 printouts
all: introduce fwk/fsm.State and fwk.FSMStater
svc,tsk: implement fwk.FSMStater
hbook: first stab at a histogram service
all: add Context.Svc(name)
hsvc: non-conc-safe impl.
test: add hbooksvc test (sequential)