Make all mutable fields in WebSocketClientHandshaker volatile

- Fixes #1945
[#1959] Proposed fix to correctly handle timeouts that overflow the ticks in the wheel
[#1959] Include a test-case
Fix a bug where ChannelFutureProgressListener.operationProgressed() isn't something invoked

- Fixes #1950
- Use writtenBytes instead of localWrittenBytes so that operationProgressed() is triggered even when write operation was split into multiple system calls.
Split HttpPostRequestDecoder into HttpPostStandardRequestDecoder and HttpPostMultipartRequestDecoder / Add HttpData.maxSize

- Related issues: #1937 #1938 and #1946
- Add InterfaceHttpPostRequestDecoder and Make HttpPostRequestDecoder
  implement it
- HttpPostRequestDecoder actually delegates itself to
  HttpPostStandardRequestDecoder or HttpPostMultipartRequestDecoder
- Deprecate IncompatibleDataDecoderException because it's not thrown
  anywhere now
Fix some inspector warnings
[maven-release-plugin] prepare release netty-3.8.0.Final
[maven-release-plugin] prepare for next development iteration