Examples fixed
Hotfix over echo example

 - stdout is now correctly flushed
Race condition have been fixed for synchronous API

 - now calling `get` won't lead to the undefined behaviour whichever how much chunks will be delivered before stopping event loop. Before fix, for example, if application sends chunk and choke, and both of them were received almost simultaneously, then event loop stopping condition was executed only after both of chunk and choke transferred to the user. If you expect chunk, you received choke and that sucks.
 - more debug logging points injected
 - `FutureResult` class's code have been slightly reduced
Another pack of documentation added