- introduce quit, drained, shutdown channels
- mainLoop falls through reading message channel to drained state, and waits is blocked in default branch until any message is sent
- Flush() waits for <-drained
- Stop() pushes quit and nodges mainloop out of blocking drained state
- package-global mutex
- Reset()
- clear tests

- consistent renaming
- React -> Event
- ReactorEvent -> EventHandler
- NewReactorEngine -> New
- async ReactorEngine main loop with select on main eventChannel and quit channel
- ReactorEngine main loop control with Start() Stop() Flush()
- ReactorEngine.dispatch
- use sync.RWMutex
- delete eventHandler if subscribed channels go to 0

* Script compile length fix
* Transition fix

Merge branch 'feature/clientid' of https://github.com/ethersphere/eth-go into ethersphere-feature/clientid

typo, duplications

- remove clientstring handling from ethutil.Config
- ReadConfig takes no Identifier argument
- members Ver, ClientString, ClientIdentifier removed from Config
- type ConfValue removed
- expose public type ethutil.ConfigManager
- Set -> Save(key string, value interface{}) now takes any value to allow for persisting non-string values directly
- TODO: eliminate all eth specific configs, just a wrapper around globalconf