rewrite SslHandler's flush0 message to match docs
Dissallow adding null elements into RecyclableArrayList
Just tiny optimization to avoid object creation
Also dissallow null elements on set
SPDY: check if spdyHeadersFrame is null before adding it to out
[#1568] Fix problem where an exception was fired after the channel was closed.

* Calling fireExceptionCaught(...) in this case was not correct as we failed writes which are outbound operations.
[#1570] ChunkedWriteHandler.discard(..) must not call fireExceptionCaught(...)
Make clear how to use HTTPS in the helloworld example
Cleanup
Cache flush(..) tasks which are used when executing with different EventExecutor to lower GC pressure
Remove unnecessary try-catch block in AbstractUnsafe.flush()
Fix a bug where ChannelOutboundBuffer.addFlush() is called multiple times
Reduce garbage in AbstractUnsafe.flush0()
Remove dead code

- Fixed #1557
Fix embarassing compilation error :-/
Add a boolean parameter to Channel.Unsafe.flush() so that SelectionKey state check can be bypassed.
Make the cumulation field in ByteToMessageDecoder package private to hide it
|| -> &&
Remove UnreplayableOperationException

- Can't find a reason to keep it.
Kill the cruft