all: use timer instead of time.After in loops, to avoid memleaks#97

FletcherMan merged 1 commit intorelease/0.3.xmorph-l2/go-ethereum:release/0.3.xfrom

cherry-pick-b3fc060636d27806ea8b329f58530c898b7d21afmorph-l2/go-ethereum:cherry-pick-b3fc060636d27806ea8b329f58530c898b7d21afCopy head branch name to clipboard