Merge pull request #3605 from fjl/event-feed

core/tx_pool.go

eth/filters/filter_system.go

eth/handler.go

event/event.go

event/event_test.go

event/example_feed_test.go

event/example_scope_test.go

event/example_subscription_test.go

event/feed.go

event/feed_test.go

event/subscription.go

event/subscription_test.go

light/txpool.go

miner/worker.go

rpc/client.go